pinctrl/abx500: add AB8540 sub-driver

Add AB8540 sub driver to the ABx500 family, pins, pin groups and
gpio range.

As the pin controller (also the ABx500 controllers) is an
inherent part of the SoC and will prevent boot if not
available, select this from the Ux500 SoC Kconfig.

Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Patrice Chotard <patrice.chotard@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/Kconfig b/drivers/pinctrl/Kconfig
index aea4ceb..0ef92cc 100644
--- a/drivers/pinctrl/Kconfig
+++ b/drivers/pinctrl/Kconfig
@@ -37,6 +37,10 @@
 	bool "AB8500 pin controller driver"
 	depends on PINCTRL_ABX500 && ARCH_U8500
 
+config PINCTRL_AB8540
+	bool "AB8540 pin controller driver"
+	depends on PINCTRL_ABX500 && ARCH_U8500
+
 config PINCTRL_AB9540
 	bool "AB9540 pin controller driver"
 	depends on PINCTRL_ABX500 && ARCH_U8500