declare device.flash options in base.nix

because they're specified in devices/*/default.nix

modules/base.nix

@@ -68,6 +68,10 @@ in {
       defaultOutput = mkOption {
         type = types.nonEmptyStr;
       };
+      flash = {
+        address = mkOption { type = types.str; };
+        size = mkOption { type = types.str; };
+      };
       loadAddress = mkOption { default = null; };
       entryPoint = mkOption { };
       radios = mkOption {

modules/flashable.nix

@@ -9,10 +9,6 @@ let
   inherit (config.boot) tftp;
 in {
   options = {
-    device.flash = {
-      address = mkOption { type = types.str; };
-      size = mkOption { type = types.str; };
-    };
   };
   config = {
     kernel = {