msm: kgsl: Patch in the mem pool size in the A6XX snapshot

The CP_MEM_POOL_SIZE register is cleared while dumping out the
mem pool indexed register section to stabilize it. This modifies
the mem pool data. Patch the original size in the snapshot data
to keep it consistent.

Change-Id: I3764224e07ea3bf656676a126eeda47de37b487f
Signed-off-by: Lynus Vaz <lvaz@codeaurora.org>