msm: camera: Add support for reg dump to command buffers

Certain register values are required by user space during flush
to apply settings accordingly. Also, support for dumping registers
at the time of error is needed for debugging. Add support for
dumping register values in a range of offsets to given cmd buffer.

Change-Id: I5912118809f7a7dd701a555639d1057ffe665ce1
Signed-off-by: Mukund Madhusudan Atre <matre@codeaurora.org>