msm: actuator: fix to prevent kernel heap buffer overflow

fix to prevent kernel heap buffer overflow allows user
controlled data to be written to the heap via the
msm_camera actuator IOCTLs

Change-Id: I4458831e28e0081fb2f5ae55506be866100e1b4f
Signed-off-by: Vasko Kalanoski <vaskok@codeaurora.org>