nixos/firmware: remove restrictive hardware.enableAllFirmware assertion (#441240)

nixos/modules/hardware/all-firmware.nix

@@ -36,7 +36,18 @@ in
 
   options = {
 
-    hardware.enableAllFirmware = lib.mkEnableOption "all firmware regardless of license";
+    hardware.enableAllFirmware = lib.mkOption {
+      default = false;
+      example = true;
+
+      description = ''
+        Whether to enable all firmware, including [unfree packages that must be explictly allowed](https://nixos.org/manual/nixpkgs/unstable/#sec-allow-unfree).
+
+        Alternatively, use the {option}`hardware.enableRedistributableFirmware` option.
+      '';
+
+      type = lib.types.bool;
+    };
 
     hardware.enableRedistributableFirmware =
       lib.mkEnableOption "firmware with a license allowing redistribution"
@@ -74,16 +85,6 @@ in
         ++ lib.optional pkgs.stdenv.hostPlatform.isAarch raspberrypiWirelessFirmware;
     })
     (lib.mkIf cfg.enableAllFirmware {
-      assertions = [
-        {
-          assertion = !cfg.enableAllFirmware || pkgs.config.allowUnfree;
-          message = ''
-            the list of hardware.enableAllFirmware contains non-redistributable licensed firmware files.
-              This requires nixpkgs.config.allowUnfree to be true.
-              An alternative is to use the hardware.enableRedistributableFirmware option.
-          '';
-        }
-      ];
       hardware.firmware =
         with pkgs;
         [