msm: kgsl: Save snapshot IB data in queued work item

Queue a work item after taking snapshot. The work item saves
the data placed in frozen objects into a separate allocated memory.
The data in frozen objects can change after snapshot is taken and
before the snapshot is dumped or pulled from the system. This work
item in between helps in getting the actual data in the objects by
saving the data in memory. Data can change in the time the work item
executes and snapshot is taken but this time gap is much smaller
compared to snapshot being pulled and snapshot being taken so it
avoids incorrect data in most known cases.

Change-Id: I77d065a5f50517440fd249101b9f0f764125bfdd
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>