msm: camera: isp: protect burst streams from invalid write

To ensure correct number of output frames, burst streams are
configured to skip all frames after delivering the last requested one.
However, the framedrop period and pattern registers are double
buffered and current implementation does not guarantee that register
update will happen on each frame. Thus, if reg update miss last frame
the burst stream write masters will make invalid write. This change
configures frame skip pattern in such manner, that all frames after
last required to be skipped. This will ensure that no extra frames
will be written and there will be enough time to receive reg update
command.

Change-Id: I3c8107bb4a426b62eb9c4a8f87857c0497b32f2c
Signed-off-by: Petar Sivenov <psiven@codeaurora.org>