msm_fb: display: Send current timestamp in case of timeout

On timeout while waiting for the vsync, send the current
timestamp to the userspace. This resolves the infinite
wait seen during the bootup.

Change-Id: Ib1426c7c9a21c37758d7352740938627d4613fd6
Signed-off-by: Siddhartha Agrawal <agrawals@codeaurora.org>