msm: camera: Fix uninitialized memory returned to userspace

Local structures have not been initialized to all zeroes, so fix
this by setting them to all zeroes to prevent uninitialized memory
being copied to userspace.

CRs-fixed: 518478
Change-Id: I6e76355c3f854514def1bd18dcc5c3ef6db38f16
Signed-off-by: Seemanta Dutta <seemanta@codeaurora.org>