msm: camera: Add live snapshot entry to bus vector table.

The current camera bus vector table does not have an entry
for Live snapshot usecase. Add this entry into the bus vector
table. When user takes a live snapshot during video recording,
just switch to this new entry and when its done, switch back
to video entry. Also, correct the .ab value for video usecase
since the current value is not sufficient for all the usecases.

Change-Id: I9c8c9ede2cf22cf8a21383e3d7868c75f21eba12
Signed-off-by: Kiran Kumar H N <hurlisal@codeaurora.org>