gpio: sifive: drop of_match_ptr for ID table

The driver can match only via the DT table so the table should be always
used and the of_match_ptr does not have any sense (this also allows ACPI
matching via PRP0001, even though it might not be relevant here).

  drivers/gpio/gpio-sifive.c:263:34: error: ‘sifive_gpio_match’ defined but not used [-Werror=unused-const-variable=]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/gpio-sifive.c

@@ -270,7 +270,7 @@ static struct platform_driver sifive_gpio_driver = {
 	.probe		= sifive_gpio_probe,
 	.driver = {
 		.name	= "sifive_gpio",
-		.of_match_table = of_match_ptr(sifive_gpio_match),
+		.of_match_table = sifive_gpio_match,
 	},
 };
 builtin_platform_driver(sifive_gpio_driver)