media: qcom: venus: Fix uninitialized variable warning

Avoid uninitialized variable when both V4L2_TYPE_IS_OUTPUT() and
V4L2_TYPE_IS_CAPTURE() return false.

Signed-off-by: Nas Chung <nas.chung@chipsnmedia.com>
Signed-off-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>