builders/uimage: support aligning the FIT

This is necessary when writing to a MTD partition with a certain erasesize.

modules/outputs.nix

@@ -111,7 +111,7 @@ in
       };
       uimage = liminix.builders.uimage {
         commandLine = concatStringsSep " " config.boot.commandLine;
-        inherit (config.hardware) loadAddress entryPoint;
+        inherit (config.hardware) loadAddress entryPoint alignment;
         inherit (config.boot) imageFormat;
         inherit (o) kernel dtb;
       };