MLK-20441-1 spi: lpspi: Add cs-gpio feature to support spi-nor

Add cs-gpio feature. Use fsl_lpspi_prepare_message() and
fsl_lpspi_unprepare_message() to enable and control cs line.
These two functions will be only called at the beginning and the ending
of a message transfer.

Still can use the mode without cs-gpio. The two ways can refer to
fsl-imx8qm-lpddr4-arm2-lpspi.dts for setting the lpspi configration in
dts file.

Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
(cherry picked from commit 245d353cdf0a461ddcd2dcc36793571aae1069b0)