kernel/generic: remove redundant kernelOlder/kernelAtLeast

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

···
     features = kernelFeatures;
     inherit commonStructuredConfig structuredExtraConfig extraMakeFlags isZen isHardened isLibre modDirVersion;
     isXen = lib.warn "The isXen attribute is deprecated. All Nixpkgs kernels that support it now have Xen enabled." true;
-    kernelOlder = lib.versionOlder version;
-    kernelAtLeast = lib.versionAtLeast version;
     passthru = kernel.passthru // (removeAttrs passthru [ "passthru" ]);
     tests = let
       overridableKernel = finalKernel // {