msm: isp: Increased the Scratch buffer size.

Scratch buffer size is not sufficient for 14 bit raw.
This leads to page fault. This change increases the size of
scratch buffer to accommodate 14 bit MIPI raw format.
CRs-Fixed: 970413

Change-Id: I866640158c11c0f69505e4fb6b12a9204e2a6ad4
Signed-off-by: Senthil Kumar Rajagopal <skrajago@codeaurora.org>