spi: sh-msiof: Use DMA if possible

Currently, this driver only supports feature for DMA 32-bits.
In this case, only if the data length is divisible by 4 to use
DMA, otherwise PIO will be used. This patch will suggest use
the DMA 32-bits with 4bytes of words, then the remaining data
will be transmitted by PIO mode.

Signed-off-by: Hoan Nguyen An <na-hoan@jinso.co.jp>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-sh-msiof.c

@@ -937,17 +937,13 @@ static int sh_msiof_transfer_one(struct spi_master *master,
 		unsigned int l = 0;
 
 		if (tx_buf)
-			l = min(len, p->tx_fifo_size * 4);
+			l = min(round_down(len, 4), p->tx_fifo_size * 4);
 		if (rx_buf)
-			l = min(len, p->rx_fifo_size * 4);
+			l = min(round_down(len, 4), p->rx_fifo_size * 4);
 
 		if (bits <= 8) {
-			if (l & 3)
-				break;
 			copy32 = copy_bswap32;
 		} else if (bits <= 16) {
-			if (l & 3)
-				break;
 			copy32 = copy_wswap32;
 		} else {
 			copy32 = copy_plain32;