As there's no upstream DT bindings for this driver, let's
update its DT schema, while it is not too late.

While here, add error messages, in order to help discovering
problems during probing time.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/746237a6bdbb84d4271a77994c82bccf524680c7.1630659949.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>