spi: bcm-qspi: Convert to use CS GPIO descriptors

Set use_gpio_descriptors to true and avoid asserting the native chip
select if the spi core has done it for us.
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Link: https://lore.kernel.org/r/20191107044235.4864-2-chris.packham@alliedtelesis.co.nzSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-bcm-qspi.c

@@ -803,6 +803,7 @@ static int bcm_qspi_bspi_exec_mem_op(struct spi_device *spi,
 			return -EIO;
 
 	from = op->addr.val;
+	if (!spi->cs_gpiod)
 		bcm_qspi_chip_select(qspi, spi->chip_select);
 	bcm_qspi_write(qspi, MSPI, MSPI_WRITE_LOCK, 0);
 
@@ -882,6 +883,7 @@ static int bcm_qspi_transfer_one(struct spi_master *master,
 	int slots;
 	unsigned long timeo = msecs_to_jiffies(100);
 
+	if (!spi->cs_gpiod)
 		bcm_qspi_chip_select(qspi, spi->chip_select);
 	qspi->trans_pos.trans = trans;
 	qspi->trans_pos.byte = 0;
@@ -1234,6 +1236,7 @@ int bcm_qspi_probe(struct platform_device *pdev,
 	master->cleanup = bcm_qspi_cleanup;
 	master->dev.of_node = dev->of_node;
 	master->num_chipselect = NUM_CHIPSELECT;
+	master->use_gpio_descriptors = true;
 
 	qspi->big_endian = of_device_is_big_endian(dev->of_node);