gpio: Adjust of_xlate API to support multiple GPIO chips

This patch changes the of_xlate API to make it possible for multiple
gpio_chips to refer to the same device tree node.  This is useful for
banked GPIO controllers that use multiple gpio_chips for a single
device.  With this change the core code will try calling of_xlate on
each gpio_chip that references the device_node and will return the
gpio number for the first one to return 'true'.

Tested-by: Roland Stigge <stigge@antcom.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 566d012..38353c0 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1156,7 +1156,7 @@
  */
 struct gpio_chip *gpiochip_find(const void *data,
 				int (*match)(struct gpio_chip *chip,
-					     const void *data))
+					     void *data))
 {
 	struct gpio_chip *chip = NULL;
 	unsigned long flags;