spi/mxs: Add SPI driver for mx233/mx28

spi/mxs: Add SPI driver for mx233/mx28

This is slightly reworked version of the SPI driver.
Support for DT has been added and it's been converted
to queued API.

Based on previous attempt by:
Fabio Estevam <fabio.estevam@freescale.com>

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Acked-by: Chris Ball <cjb@laptop.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>