msm: vidc: Fixes back-to-back video decode/encode.

Fixes a bug introduced in recent commit because of
which only one video session worked. Next video
session always failed when client tries to open
the video device.

The commit ID caused the issue is
fe72c45c

Change-Id: Ib0cbe7cac5189cf617e8b3bcfc549e022e88fd46
Signed-off-by: Vinay Kalia <vkalia@codeaurora.org>