spi: cadence_quadspi: Enable QUAD mode based on DT data

spi: cadence_quadspi: Enable QUAD mode based on DT data

Instead of relying on CONFIG_SPI_FLASH_QUAD to be defined to enable QUAD
mode, make use of mode_rx field of dm_spi_slave_platdata to determine
whether to enable or disable QUAD mode. This is necessary to support
muliple SPI controllers where one of them may not support QUAD mode.

Signed-off-by: Vignesh R <[email protected]>
Tested-by: Marek Vasut <[email protected]>
Acked-by: Marek Vasut <[email protected]>
Reviewed-by: Jagan Teki <[email protected]>