mm-video-v4l2: venc: Fix input extradata length

Input extradata length is wrongly assigned as buffer_size
instead of size before sending buffer to driver which is
resulting in qbuf failure. Update the length properly to
resolve the failure.

CRs-Fixed: 2082238
Change-Id: Ib6ee28ed047f27b87b35eca42a0f680ef9d7504a
1 file changed