`mechwild/bbpad`: fix build (#24106)

keyboards/mechwild/bbpad/keymaps/default/keymap.json

@@ -1,5 +1,5 @@
 {
-    "keyboard": "mechwild/bbpad",
+    "keyboard": "mechwild/bbpad/f401",
     "keymap": "default",
     "version": 1,
     "layout": "LAYOUT_horiz",