spi: omap2-mcspi: Fix the redifine warning

Fix the below warning
drivers/spi/spi-omap2-mcspi.c:336:34: warning: symbol 'tx' shadows an earlier one
drivers/spi/spi-omap2-mcspi.c:327:12: originally declared here

So delete the u8 tx as it is assigned and not used(resigned afterwards).
Signed-off-by: NShubhrajyoti D <shubhrajyoti@ti.com>
Acked-by: NPeter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

drivers/spi/spi-omap2-mcspi.c

@@ -324,14 +324,11 @@ static void omap2_mcspi_tx_dma(struct spi_device *spi,
 	struct omap2_mcspi	*mcspi;
 	struct omap2_mcspi_dma  *mcspi_dma;
 	unsigned int		count;
-	const u8		* tx;
 
 	mcspi = spi_master_get_devdata(spi->master);
 	mcspi_dma = &mcspi->dma_channels[spi->chip_select];
 	count = xfer->len;
 
-	tx = xfer->tx_buf;
-
 	if (mcspi_dma->dma_tx) {
 		struct dma_async_tx_descriptor *tx;
 		struct scatterlist sg;