spi: sun6i: Add support for GPIO chip select lines

Set use_gpio_descriptors as true to support using generic GPIO
lines for the chip select.
Signed-off-by: Alistair Francis <alistair@alistair23.me>
Link: https://lore.kernel.org/r/20200511045330.690507-1-alistair@alistair23.meSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-sun6i.c

@@ -470,6 +470,7 @@ static int sun6i_spi_probe(struct platform_device *pdev)
 
 	master->max_speed_hz = 100 * 1000 * 1000;
 	master->min_speed_hz = 3 * 1000;
+	master->use_gpio_descriptors = true;
 	master->set_cs = sun6i_spi_set_cs;
 	master->transfer_one = sun6i_spi_transfer_one;
 	master->num_chipselect = 4;