sunxi: pinctrl: Implement pin configuration

The sunxi pinctrl hardware has bias and drive control. Add driver
support for configuring those options.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/drivers/pinctrl/sunxi/Kconfig b/drivers/pinctrl/sunxi/Kconfig
index f4949f8..77da908 100644
--- a/drivers/pinctrl/sunxi/Kconfig
+++ b/drivers/pinctrl/sunxi/Kconfig
@@ -5,6 +5,7 @@
 config PINCTRL_SUNXI
 	select PINCTRL_FULL
 	select PINCTRL_GENERIC
+	select PINCONF
 	select PINMUX
 	bool