spi: armada-3700: Set mode bits correctly

We set SPI_RX_DUAL twice instead of setting SPI_TX_DUAL.

Fixes: 5762ab71 ("spi: Add support for Armada 3700 SPI Controller")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Romain Perier <romain.perier@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-armada-3700.c

@@ -825,7 +825,7 @@ static int a3700_spi_probe(struct platform_device *pdev)
 	master->unprepare_message = a3700_spi_unprepare_message;
 	master->set_cs = a3700_spi_set_cs;
 	master->flags = SPI_MASTER_HALF_DUPLEX;
-	master->mode_bits |= (SPI_RX_DUAL | SPI_RX_DUAL |
+	master->mode_bits |= (SPI_RX_DUAL | SPI_TX_DUAL |
 			      SPI_RX_QUAD | SPI_TX_QUAD);
 
 	platform_set_drvdata(pdev, master);