dm: Use uclass_first_device_err() where it is useful

Use this new function in places where it simplifies the code.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index d01bfc1..519052e 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -30,11 +30,9 @@
 
 	/* Since buses may not be numbered yet try a little harder with bus 0 */
 	if (ret == -ENODEV) {
-		ret = uclass_first_device(UCLASS_PCI, busp);
+		ret = uclass_first_device_err(UCLASS_PCI, busp);
 		if (ret)
 			return ret;
-		else if (!*busp)
-			return -ENODEV;
 		ret = uclass_get_device_by_seq(UCLASS_PCI, busnum, busp);
 	}