pinctrl: add pinctrl driver for Rockchip SoCs

This driver adds support the Cortex-A9 based SoCs from Rockchip,
so at least the RK2928, RK3066 (a and b) and RK3188.
Earlier Rockchip SoCs seem to use similar mechanics for gpio
handling so should be supportable with relative small changes.
Pull handling on the rk3188 is currently a stub, due to it being
a bit different to the earlier SoCs.

Pinmuxing as well as gpio (and interrupt-) handling tested on
a rk3066a based machine.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/Kconfig b/drivers/pinctrl/Kconfig
index 47cb923..269c040 100644
--- a/drivers/pinctrl/Kconfig
+++ b/drivers/pinctrl/Kconfig
@@ -158,6 +158,12 @@
 	bool "DB8540 pin controller driver"
 	depends on PINCTRL_NOMADIK && ARCH_U8500
 
+config PINCTRL_ROCKCHIP
+	bool
+	select PINMUX
+	select GENERIC_PINCONF
+	select GENERIC_IRQ_CHIP
+
 config PINCTRL_SINGLE
 	tristate "One-register-per-pin type device tree based pinctrl driver"
 	depends on OF