gpio: Adjust of_xlate API to support multiple GPIO chips

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 <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Signed-off-by: Grant Likely <[email protected]>