spi: spi_amd: Updates to set tx/rx count functions

spi: spi_amd: Updates to set tx/rx count functions

AMD SPI TX and RX counter registers are 1-byte length registers. The
existing value will be overwritten during register write, so masking is not
required.

Co-developed-by: Krishnamoorthi M <krishnamoorthi.m@amd.com>
Signed-off-by: Krishnamoorthi M <krishnamoorthi.m@amd.com>
Co-developed-by: Akshata MukundShetty <akshata.mukundshetty@amd.com>
Signed-off-by: Akshata MukundShetty <akshata.mukundshetty@amd.com>
Signed-off-by: Raju Rangoju <Raju.Rangoju@amd.com>
Link: https://patch.msgid.link/20240925133644.2922359-5-Raju.Rangoju@amd.com
Signed-off-by: Mark Brown <broonie@kernel.org>