spi: atmel: Drop unused variable

The DMA cap mask is no longer used since:
commit 7758e390 ("spi: atmel: remove compat for non DT board when requesting dma chan")
Drop it now.
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20210218132840.131898-1-tudor.ambarus@microchip.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-atmel.c

@@ -506,10 +506,6 @@ static int atmel_spi_configure_dma(struct spi_master *master,
 	struct device *dev = &as->pdev->dev;
 	int err;
 
-	dma_cap_mask_t mask;
-	dma_cap_zero(mask);
-	dma_cap_set(DMA_SLAVE, mask);
-
 	master->dma_tx = dma_request_chan(dev, "tx");
 	if (IS_ERR(master->dma_tx)) {
 		err = PTR_ERR(master->dma_tx);