msm: vidc: Keep v4l2 plane count instance-specific

Existing video driver maintains a static array of
video formats. Video instances have a pointer to this
common array. In multi-instance scenario, different
instances read/write to common structure, resulting
into invalid plane count for other instances. To
avoid such situation, keep plane count structure
specific to the instance.

CRs-Fixed: 1051541
Change-Id: I9bd487459277e509cf64c0124a2d2e3f5fdc443b
Signed-off-by: Saurabh Kothawade <skothawa@codeaurora.org>