drm/msm: Reduce fallout of fence signaling vs reclaim hangs

drm/msm: Reduce fallout of fence signaling vs reclaim hangs

Until various PM devfreq/QoS and interconnect patches land, we could
potentially trigger reclaim from gpu scheduler thread, and under enough
memory pressure that could trigger a sort of deadlock.  Eventually the
wait will timeout and we'll move on to consider other GEM objects.  But
given that there is still a potential for deadlock/stalling, we should
reduce the timeout to contain the damage.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/568031/