Under some load conditions, the result event can come back before the
command complete event. If that happens, the code would hang
indefinitely.
Rework the code to wait for both events and avoid the hang.
(From OE-Core rev: 8cfc94a4404c54bc73eab9f98d9da1f84c2135ad)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>