drm/msm: drop redundant debug output

wait_for_completion_timeout returns 0 in case of timeout and never
return < 0 so there is no additional information in printing the
value of time_left here as it will always be 0, thus it can be dropped.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>