mfd: Fix error handling if BUG() isn't enabled in WM8994

Even if we would've BUG()ed we should still tidy up after ourselves if that
isn't enabled in the kernel config.

Signed-off-by: Mark Brown <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>

drivers/mfd/wm8994-core.c

···
 		break;
 	default:
 		BUG();
-		return -EINVAL;
+		goto err;
 	}
 
 	wm8994->supplies = kzalloc(sizeof(struct regulator_bulk_data) *
···
 		break;
 	default:
 		BUG();
-		return -EINVAL;
+		goto err;
 	}
 		
 	ret = regulator_bulk_get(wm8994->dev, wm8994->num_supplies,