spi: s3c64xx: fix compiler warning in spi-s3c64xx

The Exynos 7 arm64 support now allows the S3C64xx SPI driver to be
compiled into an ARM64 kernel, so the cast from the [rt]x_dmach int
variable to a void* in this driver now triggers a warning.
Add a long cast to silence the compiler.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-s3c64xx.c

@@ -324,7 +324,7 @@ static int s3c64xx_spi_prepare_transfer(struct spi_master *spi)
 
 		/* Acquire DMA channels */
 		sdd->rx_dma.ch = dma_request_slave_channel_compat(mask, filter,
-				   (void *)sdd->rx_dma.dmach, dev, "rx");
+				   (void *)(long)sdd->rx_dma.dmach, dev, "rx");
 		if (!sdd->rx_dma.ch) {
 			dev_err(dev, "Failed to get RX DMA channel\n");
 			ret = -EBUSY;
@@ -333,7 +333,7 @@ static int s3c64xx_spi_prepare_transfer(struct spi_master *spi)
 		spi->dma_rx = sdd->rx_dma.ch;
 
 		sdd->tx_dma.ch = dma_request_slave_channel_compat(mask, filter,
-				   (void *)sdd->tx_dma.dmach, dev, "tx");
+				   (void *)(long)sdd->tx_dma.dmach, dev, "tx");
 		if (!sdd->tx_dma.ch) {
 			dev_err(dev, "Failed to get TX DMA channel\n");
 			ret = -EBUSY;