msm_fb: display: Add timeout for waiting on update

Content Adaptive BackLight userspace algo waits on UPDATE_NOTIFY to
get the screen updates. When turning off CABL, this blocking ioctl
causes the CABL threads to wait until next screen update, which may
take indefinite time.

Add timeout value to the wait_for_completion call, to make ioctl
call blocking for at most timeout value.

CRs-Fixed: 384026
Signed-off-by: Kinjal Bhavsar <kbhavsar@codeaurora.org>
(cherry picked from commit 1b6843a3a56e60e73305c66369f8ad806353e22d)

Change-Id: Ie9609b96bc19d8ec7630a35dfc0da5c79a5615c1
Signed-off-by: Gopal Goberu <ggober@codeaurora.org>
msm_fb: display: fix division-by-zero bug

Panel v_back_porch could be zero for virtual panels, so the check for
zero is added to fix the bug.

Change-Id: I6a29f3d8d771092bca2374cc9a1c11dd77ad569e
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>