mfd: sun4i: Drop of_match_ptr from of_device_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 is not relevant here).  This fixes
compile warning (!CONFIG_OF on x86_64):

  drivers/mfd/sun4i-gpadc.c:79:34: warning: ‘sun4i_gpadc_of_match’ defined but not used [-Wunused-const-variable=]
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/sun4i-gpadc.c

@@ -166,7 +166,7 @@ static int sun4i_gpadc_probe(struct platform_device *pdev)
 static struct platform_driver sun4i_gpadc_driver = {
 	.driver = {
 		.name = "sun4i-gpadc",
-		.of_match_table = of_match_ptr(sun4i_gpadc_of_match),
+		.of_match_table = sun4i_gpadc_of_match,
 	},
 	.probe = sun4i_gpadc_probe,
 };