spi: dw: Zero DMA Tx and Rx configurations on stack

Some DMA controller drivers do not tolerate non-zero values in
the DMA configuration structures. Zero them to avoid issues with
such DMA controller drivers. Even despite above this is a good
practice per se.

Fixes: 7063c0d ("spi/dw_spi: add DMA support")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Feng Tang <feng.tang@intel.com>
Cc: Feng Tang <feng.tang@intel.com>
Link: https://lore.kernel.org/r/20200506153025.21441-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-dw-mid.c

@@ -147,6 +147,7 @@ static struct dma_async_tx_descriptor *dw_spi_dma_prepare_tx(struct dw_spi *dws,
 	if (!xfer->tx_buf)
 		return NULL;
 
+	memset(&txconf, 0, sizeof(txconf));
 	txconf.direction = DMA_MEM_TO_DEV;
 	txconf.dst_addr = dws->dma_addr;
 	txconf.dst_maxburst = 16;
@@ -193,6 +194,7 @@ static struct dma_async_tx_descriptor *dw_spi_dma_prepare_rx(struct dw_spi *dws,
 	if (!xfer->rx_buf)
 		return NULL;
 
+	memset(&rxconf, 0, sizeof(rxconf));
 	rxconf.direction = DMA_DEV_TO_MEM;
 	rxconf.src_addr = dws->dma_addr;
 	rxconf.src_maxburst = 16;