msm: camera: remove 512 bytes limitation from ctrlcmd payload.

This change removes the 512 bytes length limitation from the
payload data passed to the server thread, as part of the control
commands

Change-Id: I871b6a6d467f86431bb5d701784231d7142d60d2
Signed-off-by: Ankit Premrajka <ankitp@codeaurora.org>