The NFC controller used to accelerate the NAND transfers on SAMA5 chips
can use either RB_EDGE0 or RB_EDGE3 as its ready/busy interrupt bit.

Use the controller's compatible string to select the correct bit.

For the binding:
Acked-by: NRob Herring <robh@kernel.org>
Reviewed-by: NWenyou Yang <Wenyou.yang@atmel.com>
Tested-by: NWenyou Yang <wenyou.yang@atmel.com>
Reviewed-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: NRomain Izard <romain.izard.pro@gmail.com>
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>