regulator: stpmic1: 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 <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/stpmic1_regulator.c

@@ -441,7 +441,7 @@ static unsigned int stpmic1_map_mode(unsigned int mode)
 	case STPMIC1_BUCK_MODE_LP:
 		return REGULATOR_MODE_STANDBY;
 	default:
-		return -EINVAL;
+		return REGULATOR_MODE_INVALID;
 	}
 }