spi/omap-mcspi: Fix the spi task hangs waiting dma_rx

The spi hangs waiting the completion of omap2_mcspi_rx_callback.

Signed-off-by: Jorge A. Ventura <jorge.araujo.ventura@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Cc: stable@vger.kernel.org
diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 68441fa..352eed7 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -329,7 +329,8 @@
 disable_fifo:
 	if (t->rx_buf != NULL)
 		chconf &= ~OMAP2_MCSPI_CHCONF_FFER;
-	else
+
+	if (t->tx_buf != NULL)
 		chconf &= ~OMAP2_MCSPI_CHCONF_FFET;
 
 	mcspi_write_chconf0(spi, chconf);