x86: gpio: add pinctrl support from the device tree

Every pin can be configured now from the device tree. A dt-bindings
has been added to describe the different property available.

Change-Id: I1668886062655f83700d0e7bbbe3ad09b19ee975
Signed-off-by: Gabriel Huau <contact@huau-gabriel.fr>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/include/asm/gpio.h b/arch/x86/include/asm/gpio.h
index 1099427..ed85b08 100644
--- a/arch/x86/include/asm/gpio.h
+++ b/arch/x86/include/asm/gpio.h
@@ -147,6 +147,7 @@
 	} set3;
 };
 
+int gpio_ich6_pinctrl_init(void);
 void setup_pch_gpios(u16 gpiobase, const struct pch_gpio_map *gpio);
 void ich_gpio_set_gpio_map(const struct pch_gpio_map *map);