spi: dt-bindings: samsung: make dma properties not required

spi: dt-bindings: samsung: make dma properties not required

Since the addition of the driver in 2009, the driver selects between DMA
and polling mode depending on the transfer length - DMA mode for
transfers bigger than the FIFO depth, polling mode otherwise. All
versions of the IP support polling mode, make the dma properties not
required.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://msgid.link/r/20240301115546.2266676-1-tudor.ambarus@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>