regulator: rk808: Return REGULATOR_MODE_INVALID for invalid mode

-EINVAL is not a valid return value for .of_map_mode, return
REGULATOR_MODE_INVALID instead.

Signed-off-by: Axel Lin <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

drivers/regulator/rk808-regulator.c

···
 	case 2:
 		return REGULATOR_MODE_NORMAL;
 	default:
-		return -EINVAL;
+		return REGULATOR_MODE_INVALID;
 	}
 }