dmaengine: xilinx: xdma: Fix regmap init error handling

devm_regmap_init_mmio returns an ERR_PTR() upon error, not NULL.
Fix the error check and also fix the error message. Use the error code
from ERR_PTR() instead of the wrong value in ret.

Fixes: 17ce252 ("dmaengine: xilinx: xdma: Add xilinx xdma driver")
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20251014061309.283468-1-alexander.stein@ew.tq-group.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: tq-steina

drivers/dma/xilinx/xdma.c

@@ -1234,8 +1234,8 @@ static int xdma_probe(struct platform_device *pdev)
 
 	xdev->rmap = devm_regmap_init_mmio(&pdev->dev, reg_base,
 					   &xdma_regmap_config);
-	if (!xdev->rmap) {
-		xdma_err(xdev, "config regmap failed: %d", ret);
+	if (IS_ERR(xdev->rmap)) {
+		xdma_err(xdev, "config regmap failed: %pe", xdev->rmap);
 		goto failed;
 	}
 	INIT_LIST_HEAD(&xdev->dma_dev.channels);