linux: remove modDirVersionArg argument

It's redundant with `argsOverride.modDirVersion`.

pkgs/os-specific/linux/kernel/linux-4.14.nix

@@ -1,4 +1,4 @@
-{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, modDirVersionArg ? null, ... } @ args:
+{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, ... } @ args:
 
 with lib;
 
@@ -16,4 +16,3 @@ buildLinux (args // rec {
     sha256 = "102c9h0byr9v4bxzkdh7mnw1grm47ji6lf6l1gjlwah7f46j6ap3";
   };
 } // (args.argsOverride or {}))
-  // lib.optionalAttrs (modDirVersionArg != null) { modDirVersion = modDirVersionArg; } # legacy

pkgs/os-specific/linux/kernel/linux-4.19.nix

@@ -1,4 +1,4 @@
-{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, modDirVersionArg ? null, ... } @ args:
+{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, ... } @ args:
 
 with lib;
 
@@ -16,4 +16,3 @@ buildLinux (args // rec {
     sha256 = "02mjb16xxfj984vibpxvhjl84y5yg0jgzjccjdxnn8db4k9aa2vf";
   };
 } // (args.argsOverride or {}))
-  // lib.optionalAttrs (modDirVersionArg != null) { modDirVersion = modDirVersionArg; } # legacy

pkgs/os-specific/linux/kernel/linux-5.10.nix

@@ -1,4 +1,4 @@
-{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, modDirVersionArg ? null, ... } @ args:
+{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, ... } @ args:
 
 with lib;
 
@@ -16,4 +16,3 @@ buildLinux (args // rec {
     sha256 = "19yfi5vknxnw0cb8274q3pb5zjs6ny04n16m8xjdfdmznrbvza8v";
   };
 } // (args.argsOverride or {}))
-  // lib.optionalAttrs (modDirVersionArg != null) { modDirVersion = modDirVersionArg; } # legacy

pkgs/os-specific/linux/kernel/linux-5.15.nix

@@ -1,4 +1,4 @@
-{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, modDirVersionArg ? null, ... } @ args:
+{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, ... } @ args:
 
 with lib;
 
@@ -16,4 +16,3 @@ buildLinux (args // rec {
     sha256 = "1wvzfhzqq9dps508wmp2gblfz93ipppnjzqm0n8pi1acq11hhna0";
   };
 } // (args.argsOverride or { }))
-  // lib.optionalAttrs (modDirVersionArg != null) { modDirVersion = modDirVersionArg; } # legacy

pkgs/os-specific/linux/kernel/linux-5.4.nix

@@ -1,4 +1,4 @@
-{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, modDirVersionArg ? null, ... } @ args:
+{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, ... } @ args:
 
 with lib;
 
@@ -16,4 +16,3 @@ buildLinux (args // rec {
     sha256 = "14q5gy48j78vwnqivrgpdhj778n2jq5l7yiw5na1rwqmfh1wbvsy";
   };
 } // (args.argsOverride or {}))
-  // lib.optionalAttrs (modDirVersionArg != null) { modDirVersion = modDirVersionArg; } # legacy

pkgs/os-specific/linux/kernel/linux-6.0.nix

@@ -1,4 +1,4 @@
-{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, modDirVersionArg ? null, ... } @ args:
+{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, ... } @ args:
 
 with lib;
 
@@ -16,4 +16,3 @@ buildLinux (args // rec {
     sha256 = "191dlxcmbx8vy6z2k04jq2kr6hwnaknsnsyycvqnjmvmdf6i3lq8";
   };
 } // (args.argsOverride or { }))
-  // lib.optionalAttrs (modDirVersionArg != null) { modDirVersion = modDirVersionArg; } # legacy

pkgs/os-specific/linux/kernel/linux-6.1.nix

@@ -1,4 +1,4 @@
-{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, modDirVersionArg ? null, ... } @ args:
+{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, ... } @ args:
 
 with lib;
 
@@ -16,4 +16,3 @@ buildLinux (args // rec {
     sha256 = "sha256-LKHxcFGkMPb+0RluSVJxdQcXGs/ZfZZXchJQJwOyXes=";
   };
 } // (args.argsOverride or { }))
-  // lib.optionalAttrs (modDirVersionArg != null) { modDirVersion = modDirVersionArg; } # legacy

pkgs/os-specific/linux/kernel/linux-testing.nix

@@ -1,4 +1,4 @@
-{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, modDirVersionArg ? null, ... } @ args:
+{ lib, buildPackages, fetchurl, perl, buildLinux, nixosTests, ... } @ args:
 
 with lib;
 
@@ -18,4 +18,3 @@ buildLinux (args // rec {
   extraMeta.hydraPlatforms = [];
 
 } // (args.argsOverride or {}))
-  // lib.optionalAttrs (modDirVersionArg != null) { modDirVersion = modDirVersionArg; } # legacy