msm_fb: display: fix the suspend/resume hang caused by wait4vsync stuck

wait_for_completion in wait4vsync stucks after multiple suspend/resume
tests. The cause is that when show_event timeout happens, or vsync isr
is disabled for long time, wait_vsync_cnt resets to zero, and in vsync
isr complete_all has no chance to be called which caused mdp hang. So
complete_all needs to be called whenever show_event has timeouts.

Change-Id: I8ed9fe1814ed2ab1bd461826c31849975bf8b4ed
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>