spi: Remove SPI_RX_FAST

spi: Remove SPI_RX_FAST

Removed SPI_RX_FAST since default read for spi slaves
are always 1-wire fast read.

Cc: Simon Glass <[email protected]>
Cc: Bin Meng <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Siva Durga Prasad Paladugu <[email protected]>
Cc: Vignesh R <[email protected]>
Cc: Mugunthan V N <[email protected]>
Signed-off-by: Jagan Teki <[email protected]>