msm: vidc: Fix memory leak issue

kmemdup, which is used to copy memory also allocates
memory before copying, so no need to allocate with
kzalloc.

Change-Id: Id54a289d19284ca5e4d203e47e7db3028ad5f68d
Signed-off-by: Jayasena Sangaraboina <jsanga@codeaurora.org>