spi: gpio: Advertise support for SPI_CS_HIGH

The spi-gpio driver already handles different chip select polarities,
but so far this was not advertised in master->mode_bits.

This patch fixes mmc_spi on top of spi_gpio, which is useful in some
testing scenarios.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-gpio.c

@@ -428,7 +428,8 @@ static int spi_gpio_probe(struct platform_device *pdev)
 		return status;
 
 	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
-	master->mode_bits = SPI_3WIRE | SPI_3WIRE_HIZ | SPI_CPHA | SPI_CPOL;
+	master->mode_bits = SPI_3WIRE | SPI_3WIRE_HIZ | SPI_CPHA | SPI_CPOL |
+			    SPI_CS_HIGH;
 	master->flags = master_flags;
 	master->bus_num = pdev->id;
 	/* The master needs to think there is a chipselect even if not connected */