spi: spi-cadence: Enable spi refclk in slave mode

When spi-cadence is configured as a slave, it requires the SPI refclk to
detect the synchronization start condition while communicating with the
master. However, the spi-cadence driver never enables the SPI refclk in
slave mode, causing the refclk to remain disabled if the
"clk_ignore_unused" kernel parameter is not passed through bootargs.
As a result, the slave cannot detect data sent by the master, leading to
communication failure. Update driver to enable the SPI refclk in both
master and slave configurations.

Fixes: b1b90514 ("spi: spi-cadence: Add support for Slave mode")
Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>
Link: https://msgid.link/r/20240617153837.29861-1-amit.kumar-mahapatra@amd.com


Signed-off-by: Mark Brown <broonie@kernel.org>