spi: rockchip: use designated init for dma config

Use C99 designated initializers for dma slave config
structures. This also makes sure uninitialized fields
are zeroed so we don't need an explicit memset.
Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-rockchip.c

@@ -442,12 +442,8 @@ static void rockchip_spi_dma_txcb(void *data)
 static int rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 {
 	unsigned long flags;
-	struct dma_slave_config rxconf, txconf;
 	struct dma_async_tx_descriptor *rxdesc, *txdesc;
 
-	memset(&rxconf, 0, sizeof(rxconf));
-	memset(&txconf, 0, sizeof(txconf));
-
 	spin_lock_irqsave(&rs->lock, flags);
 	rs->state &= ~RXBUSY;
 	rs->state &= ~TXBUSY;
@@ -455,10 +451,13 @@ static int rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 
 	rxdesc = NULL;
 	if (rs->rx) {
-		rxconf.direction = DMA_DEV_TO_MEM;
-		rxconf.src_addr = rs->dma_rx.addr;
-		rxconf.src_addr_width = rs->n_bytes;
-		rxconf.src_maxburst = 1;
+		struct dma_slave_config rxconf = {
+			.direction = DMA_DEV_TO_MEM,
+			.src_addr = rs->dma_rx.addr,
+			.src_addr_width = rs->n_bytes,
+			.src_maxburst = 1,
+		};
+
 		dmaengine_slave_config(rs->dma_rx.ch, &rxconf);
 
 		rxdesc = dmaengine_prep_slave_sg(
@@ -474,10 +473,13 @@ static int rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 
 	txdesc = NULL;
 	if (rs->tx) {
-		txconf.direction = DMA_MEM_TO_DEV;
-		txconf.dst_addr = rs->dma_tx.addr;
-		txconf.dst_addr_width = rs->n_bytes;
-		txconf.dst_maxburst = rs->fifo_len / 2;
+		struct dma_slave_config txconf = {
+			.direction = DMA_MEM_TO_DEV,
+			.dst_addr = rs->dma_tx.addr,
+			.dst_addr_width = rs->n_bytes,
+			.dst_maxburst = rs->fifo_len / 2,
+		};
+
 		dmaengine_slave_config(rs->dma_tx.ch, &txconf);
 
 		txdesc = dmaengine_prep_slave_sg(