drivers: spi_sedi: correct CPOL and CPHA mode handling in SPI config

The CPOL and CPHA mode handling logic in the SPI configuration was
corrected to ensure proper evaluation of the SPI mode bits.
Evaluate CPOL and CPHA bits using value of cpol_mode and cpha_mode:
`(SPI_MODE_GET(config->operation) & SPI_MODE_CPOL) != 0` and
`(SPI_MODE_GET(config->operation) & SPI_MODE_CPHA) != 0`.

This fix ensures that the SPI configuration is robust and adheres to
expected behavior when setting CPOL and CPHA modes.

Signed-off-by: Xiaolu Sun <xiaolu.sun@intel.com>