pinctrl: add nexell driver

Changes in relation to FriendlyARM's U-Boot nanopi2-v2016.01:
- livetree API (dev_read_...) is used instead of fdt one (fdt...).
- doc/device-tree-bindings/pinctrl/nexell,s5pxx18-pinctrl.txt added.

Signed-off-by: Stefan Bosch <stefan_b@posteo.net>
diff --git a/drivers/pinctrl/Kconfig b/drivers/pinctrl/Kconfig
index 83e39b9..bd2061b 100644
--- a/drivers/pinctrl/Kconfig
+++ b/drivers/pinctrl/Kconfig
@@ -294,6 +294,7 @@
 source "drivers/pinctrl/mscc/Kconfig"
 source "drivers/pinctrl/mtmips/Kconfig"
 source "drivers/pinctrl/mvebu/Kconfig"
+source "drivers/pinctrl/nexell/Kconfig"
 source "drivers/pinctrl/nxp/Kconfig"
 source "drivers/pinctrl/renesas/Kconfig"
 source "drivers/pinctrl/rockchip/Kconfig"