spi: dw: Remove misleading comment for Mount Evans SoC

Remove a misleading comment about the DMA operations of the Intel Mount
Evans SoC's SPI Controller as requested by Serge.

Signed-off-by: Abe Kohandel <abe.kohandel@intel.com>
Link: https://lore.kernel.org/linux-spi/20230606191333.247ucbf7h3tlooxf@mobilestation/
Fixes: 0760d5d0

 ("spi: dw: Add compatible for Intel Mount Evans SoC")
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Link: https://lore.kernel.org/r/20230606231844.726272-1-abe.kohandel@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>