sunxi: pinctrl: Create the driver skeleton

Create a do-nothing driver for each sunxi pin controller variant.

Since only one driver can automatically bind to a DT node, since the
GPIO driver already requires a manual binding process, and since the
pinctrl driver needs access to some of the same information, refactor
the GPIO driver to be bound by the pinctrl driver. This commit should
cause no functional change.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 4567c18..ea3d7ec 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1072,6 +1072,7 @@
 	select OF_BOARD_SETUP
 	select OF_CONTROL
 	select OF_SEPARATE
+	select PINCTRL
 	select SPECIFY_CONSOLE_INDEX
 	select SPL_SEPARATE_BSS if SPL
 	select SPL_STACK_R if SPL