spi: spi-fsl-dspi: Use DMA for S32G controller in target mode

spi: spi-fsl-dspi: Use DMA for S32G controller in target mode

Switch to DMA for target mode otherwise the controller is too slow to
feed TX FIFO and UNDERFLOW occurs frequently. DMA can work only with 8
and 16 bits per word. 32bits per word is not supported, this is a
hardware limitation, so we keep the controller mode in TCFQ mode.

Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@nxp.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Link: https://patch.msgid.link/20250522-james-nxp-spi-v2-9-bea884630cfb@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>