gpio: xgene-sb: Drop redundant OF_GPIO dependency

There is nothing in the driver requires OF_GPIO. Moreover, driver
supports ACPI and OF_GPIO may be a quite overhead on such configurations.

Drop dependency for good and replace of_gpio.h to of.h since we have
one function to be defined from there.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200512182721.55127-1-andriy.shevchenko@linux.intel.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/Kconfig

@@ -638,7 +638,7 @@ config GPIO_XGENE
 
 config GPIO_XGENE_SB
 	tristate "APM X-Gene GPIO standby controller support"
-	depends on ARCH_XGENE && OF_GPIO
+	depends on ARCH_XGENE
 	select GPIO_GENERIC
 	select GPIOLIB_IRQCHIP
 	select IRQ_DOMAIN_HIERARCHY

drivers/gpio/gpio-xgene-sb.c

@@ -10,8 +10,8 @@
 
 #include <linux/module.h>
 #include <linux/io.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
-#include <linux/of_gpio.h>
 #include <linux/gpio/driver.h>
 #include <linux/acpi.h>