Input: ads7846: do not overwrite spi->mode flags set by spi framework

Do not overwrite spi->mode flags set by spi framework, otherwise the
chip select polarity will get lost.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Link: https://lore.kernel.org/r/20201027095724.18654-3-o.rempel@pengutronix.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/input/touchscreen/ads7846.c

@@ -1288,7 +1288,8 @@ static int ads7846_probe(struct spi_device *spi)
 	 * may not.  So we stick to very-portable 8 bit words, both RX and TX.
 	 */
 	spi->bits_per_word = 8;
-	spi->mode = SPI_MODE_0;
+	spi->mode &= ~SPI_MODE_X_MASK;
+	spi->mode |= SPI_MODE_0;
 	err = spi_setup(spi);
 	if (err < 0)
 		return err;