dmaengine: xilinx_dma: fix style issues from checkpatch

This patch fixes below.
ERROR: open brace '{' following function definitions go on the next line
+static int xilinx_dma_child_probe(struct xilinx_dma_device *xdev,
+				    struct device_node *node) {

Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>