spi: Remove SPI_OPM_RX_EXTN

spi: Remove SPI_OPM_RX_EXTN

SPI_OPM_RX_EXTN is a combination of all rx opmode's
and spi driver shall use any one of the rx mode at
a time not the combination and it is true in case of
flash where spi_flash_table mention combination of
supported read opmodes so-that the required one
will pick based on the rx mode from spi driver.

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