dm: core: Update log method for uclass_find_device_by_seq

Use log() insted of debug() for uclass_find_device_by_seq function,
since this print is very much and we can filter it out with log()
interface.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Move #define to top of file as per docs:
Signed-off-by: Simon Glass <sjg@chromium.org>