spi: spi-mxs: Remove full duplex check, spi core already does it

Because the driver sets the SPI_MASTER_HALF_DUPLEX flag, the spi core
will check transfers to insure they are not full duplex.  It's not
necessary to check that in the spi-mxs driver as well.
Signed-off-by: Trent Piepho <tpiepho@gmail.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-mxs.c

@@ -399,12 +399,6 @@ static int mxs_spi_transfer_one(struct spi_master *master,
 		/* De-assert on last transfer, inverted by cs_change flag */
 		flag = (&t->transfer_list == m->transfers.prev) ^ t->cs_change ?
 		       TXRX_DEASSERT_CS : 0;
-		if ((t->rx_buf && t->tx_buf) || (t->rx_dma && t->tx_dma)) {
-			dev_err(ssp->dev,
-				"Cannot send and receive simultaneously\n");
-			status = -EINVAL;
-			break;
-		}
 
 		/*
 		 * Small blocks can be transfered via PIO.