spi: img-spfi: Increase DMA burst size

A 1-byte burst size is rather inefficient and has been shown to cause
TX issues during testing.  Increase the DMA burst size to 4-bytes for
both RX and TX DMA when using the 8-bit FIFO.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-img-spfi.c

@@ -341,7 +341,7 @@ static int img_spfi_start_dma(struct spi_master *master,
 		default:
 			rxconf.src_addr = spfi->phys + SPFI_RX_8BIT_VALID_DATA;
 			rxconf.src_addr_width = 1;
-			rxconf.src_maxburst = 1;
+			rxconf.src_maxburst = 4;
 		}
 		dmaengine_slave_config(spfi->rx_ch, &rxconf);
 
@@ -368,7 +368,7 @@ static int img_spfi_start_dma(struct spi_master *master,
 		default:
 			txconf.dst_addr = spfi->phys + SPFI_TX_8BIT_VALID_DATA;
 			txconf.dst_addr_width = 1;
-			txconf.dst_maxburst = 1;
+			txconf.dst_maxburst = 4;
 			break;
 		}
 		dmaengine_slave_config(spfi->tx_ch, &txconf);