spi: mxic: Fix DMAS_CTRL register layout

Fix the current layout which only matches early non-public revisions
of the IP. Since its official distribution, two bytes of the SPI
controller DMAS_CTRL register have been inverted.

Suggested-by: Mason Yang <masonccyang@mxic.com.tw>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20190919202504.9619-4-miquel.raynal@bootlin.com


Signed-off-by: Mark Brown <broonie@kernel.org>