Since the SSP controller can act as both SPI and MMC host,
renaming the enum to properly reflect the naming seems
appropriate.

Based on previous attempt by:
Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NMarek Vasut <marex@denx.de>
Acked-by: NChris Ball <cjb@laptop.org>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>