spi: atmel: Remove setting of deprecated member of struct dma_slave_config

spi: atmel: Remove setting of deprecated member of struct dma_slave_config

The 'direction' member of 'struct dma_slave_config' is deprecated.
Instead, drivers should use the direction argument to the
device_prep_slave_sg and device_prep_dma_cyclic functions or the
dir field in the dma_interleaved_template structure.
spi-atmel uses the direction argument to dmaengine_prep_slave_sg.
slave_config.direction is not used in neither of the DMA controller
drivers (at_h/xdmac) that spi-atmel is using, we can just remove the
setting of slave_config.direction and live with whatever stack value
is there.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20211125124110.838037-3-tudor.ambarus@microchip.com
Signed-off-by: Mark Brown <broonie@kernel.org>