uboot-imx

dm: Provide better debugging when a device fails to bind

All devices should bind without error. But when they don't, they can cause
driver model init to fail. A real situation where this can happen is when
there is a missing uclass.

Add a debug() call to dm_scan_fdt_node to make this easier to track.

Signed-off-by: Simon Glass <sjg@chromium.org>