Support i.mx7d.
quadspi in i.mx7d increase rxfifo.
require fill at least 16byte to trigger data transfer.
Signed-off-by: NFrank Li <Frank.Li@freescale.com>
Signed-off-by: NHan Xu <han.xu@freescale.com>
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>