fixup! dmaengine: dw-axi-dmac: Add DMA channel selection

* Fixes build with Clang.

drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c:1513:3: error: variable 'chan_flags_all' is uninitialized when used here [-Werror,-Wuninitialized]
 1513 |                 chan_flags_all |= dw->chan_flags[i];
      |                 ^~~~~~~~~~~~~~
drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c:1502:25: note: initialize the variable 'chan_flags_all' to silence this warning
 1502 |         uint32_t chan_flags_all;
      |                                ^
      |                                 = 0
1 error generated.

Author: KonstaT

drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c

@@ -1497,7 +1497,7 @@ static struct dma_chan *dw_axi_dma_of_xlate(struct of_phandle_args *dma_spec,
 {
 	struct dw_axi_dma *dw = ofdma->of_dma_data;
 	struct axi_dma_chan *chan;
-	uint32_t chan_flags_all;
+	uint32_t chan_flags_all = 0;
 	uint32_t busy_channels;
 	struct dma_chan *dchan;
 	dma_cap_mask_t mask;