spi: spi-fsl-dspi: Don't mask off undefined bits

This is a useless operation, and if the driver needs to do that, there's
something deeply wrong going on.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20200304220044.11193-4-olteanv@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-fsl-dspi.c

@@ -274,9 +274,6 @@ static void dspi_push_rx(struct fsl_dspi *dspi, u32 rxdata)
 	if (!dspi->rx)
 		return;
 
-	/* Mask off undefined bits */
-	rxdata &= (1 << dspi->bits_per_word) - 1;
-
 	memcpy(dspi->rx, &rxdata, dspi->bytes_per_word);
 	dspi->rx += dspi->bytes_per_word;
 }