spi-geni-qcom: remove manual CS control

spi-geni-qcom: remove manual CS control

The GPI_DMA mode already uses automatic CS control, to use automatic CS
control for non-GPI case all that's needed is to set the FRAGMENTATION flag
using the same logic as setup_gsi_xfer(). (note clearing SPI_TRANS_CFG's
CS_TOGGLE bit enables automatic CS control, the comment was wrong)

spi_geni_set_cs() is slow, so this is a big performance improvement.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Link: https://patch.msgid.link/20251120211204.24078-1-jonathan@marek.ca
Signed-off-by: Mark Brown <broonie@kernel.org>