nixos/filesystems/exfat: use "exfatprogs" instead of "exfat" if kernel > 5.7

5.7+ comes with a native exfat implementation, exfatprogs should be used instead.

The exfat package puts a "mount.exfat" binary in the path, which causes
mount to prefer the FUSE version to the non-fuse one. There's no way to
disable the binary, so switch to exfatprogs.

nixos/modules/tasks/filesystems/exfat.nix

@@ -4,8 +4,10 @@ with lib;
 
 {
   config = mkIf (any (fs: fs == "exfat") config.boot.supportedFilesystems) {
-
-    system.fsPackages = [ pkgs.exfat ];
-
+    system.fsPackages = if config.boot.kernelPackages.kernelOlder "5.7" then [
+      pkgs.exfat # FUSE
+    ] else [
+      pkgs.exfatprogs # non-FUSE
+    ];
   };
 }