NAND uses wait pin only to indicate device readiness after
a block/page operation. It is not use to extend individual
read/write cycle and so read/write wait pin monitoring must
be disabled for NAND.

Add gpmc wait pin information as the NAND uses wait pin 0
for device ready indication.
Signed-off-by: NRoger Quadros <rogerq@ti.com>
Reviewed-by: NPekon Gupta <pekon@pek-sem.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>