dm: spi: Convert Freescale QSPI driver to driver model

Move the Freescale QSPI driver over to driver model.

Signed-off-by: Haikun Wang <Haikun.Wang@freescale.com>
Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Tested-by: Peng Fan <Peng.Fan@freescale.com>
Acked-by: Simon Glass <sjg@chromium.org>