spi: Rename SPI_OPM_RX_* to SPI_RX_*

spi: Rename SPI_OPM_RX_* to SPI_RX_*

SPI_OPM_RX_AS 	- SPI_RX_SLOW
SPI_OPM_RX_AF	- SPI_RX_FAST
SPI_OPM_RX_DOUT	- SPI_RX_DUAL
SPI_OPM_RX_QOF	- SPI_RX_QUAD

Cc: Simon Glass <sjg@chromium.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Tested-by: Mugunthan V N <mugunthanvnm@ti.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Jagan Teki <jteki@openedev.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Jagan Teki <jteki@openedev.com>