drm_hwcomposer: Increase the virtual display compositor's fence timeout

drm_hwcomposer: Increase the virtual display compositor's fence timeout

50ms isn't enough time for some CTS tests (namely testSetLocalFocus). Increase
the timeout to 3 seconds, since we're not too worried about recovery time
from fence timeouts any longer.

Bug: 24362649
Test: Run cts test in a loop, ensuring the virtual compositor doesn't time out:
        run cts --loop  --class android.view.cts.WindowTest --method testSetLocalFocus --disable-reboot --min-loop-time 100 --max-random-loop-time 200

Change-Id: I5552ece3f6fe95d78a4e0770c1e30c96f2e75313
Signed-off-by: Sean Paul <seanpaul@chromium.org>