msm: vidc: Fix kw reported issues.

Fix kw reported issues related to use of uninitialized variables
and possible out of memory bound access.

CRs-Fixed: 997966
Change-Id: I66973d7dcc0988dba36da4b3c0e01484847a7a7e
Signed-off-by: Abdulla Anam <abdullahanam@codeaurora.org>