gpiolib: acpi: Fix fall-through warnings for Clang

In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning
by explicitly adding a break statement instead of letting the code fall
through to the next case.

Link: https://github.com/KSPP/linux/issues/115
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

drivers/gpio/gpiolib-acpi.c

@@ -548,6 +548,7 @@ acpi_gpio_to_gpiod_flags(const struct acpi_resource_gpio *agpio)
 		default:
 			break;
 		}
+		break;
 	default:
 		break;
 	}