spi: spi-zynqmp-gqspi: Avoid setting baud rate multiple times for same SPI frequency

spi: spi-zynqmp-gqspi: Avoid setting baud rate multiple times for same SPI frequency

During every transfer the GQSPI driver configures the baud rate value. But
when there is no change in the SPI clock frequency the driver should avoid
rewriting the same baud rate value to the configuration register. Update
GQSPI driver to rewrite the baud rate value if there is any change in SPI
clock frequency.

Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>
Link: https://lore.kernel.org/r/20221011062040.12116-4-amit.kumar-mahapatra@amd.com
Signed-off-by: Mark Brown <broonie@kernel.org>