sunxi: move SUNXI_GPIO to Kconfig

Probably for no particular reason SUNXI_GPIO was still defined the "old
way", in header files only.

Introduce SUNXI_GPIO to the Kconfig file in drivers/gpio to remove
another line from our dreadful config_whitelist.txt.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com> # Pine-H64
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

arch/arm/Kconfig

@@ -936,6 +936,7 @@ config ARCH_SUNXI
 	select SPL_STACK_R if SPL
 	select SPL_SYS_MALLOC_SIMPLE if SPL
 	select SPL_SYS_THUMB_BUILD if !ARM64
+	select SUNXI_GPIO
 	select SYS_NS16550
 	select SYS_THUMB_BUILD if !ARM64
 	select USB if DISTRO_DEFAULTS

drivers/gpio/Kconfig

@@ -215,6 +215,12 @@ config SANDBOX_GPIO_COUNT
 	  of 'anonymous' GPIOs that do not belong to any device or bank.
 	  Select a suitable value depending on your needs.
 
+config SUNXI_GPIO
+	bool "Allwinner GPIO driver"
+	depends on ARCH_SUNXI
+	help
+	  Support the GPIO device in Allwinner SoCs.
+
 config XILINX_GPIO
 	bool "Xilinx GPIO driver"
 	depends on DM_GPIO

include/configs/sunxi-common.h

@@ -257,9 +257,6 @@ extern int soft_i2c_gpio_scl;
 #endif
 #endif /* ifdef CONFIG_REQUIRE_SERIAL_CONSOLE */
 
-/* GPIO */
-#define CONFIG_SUNXI_GPIO
-
 #ifdef CONFIG_VIDEO_SUNXI
 /*
  * The amount of RAM to keep free at the top of RAM when relocating u-boot,

scripts/config_whitelist.txt

@@ -1832,7 +1832,6 @@ CONFIG_STV0991
 CONFIG_STV0991_HZ
 CONFIG_STV0991_HZ_CLOCK
 CONFIG_ST_SMI
-CONFIG_SUNXI_GPIO
 CONFIG_SUNXI_MAX_FB_SIZE
 CONFIG_SUVD3
 CONFIG_SXNI855T