msm: camera2: cpp: Set exact size for firmware loading.

The poll reads after during and after firmware loading fails.
This is because the exact size of firmware changes with the
version of the firmware. This change uses the firmware size
based on actual firmware file being loaded.

Change-Id: I949954347a48d0b388b11b3c81fd5d1a4627cbf7
Signed-off-by: Rajakumar Govindaram <rajakuma@codeaurora.org>