msm: camera2: cpp: Avoid stream count increment during delete buffer

VIDIOC_MSM_CPP_DELETE_STREAM_BUFF should avoid calling a new queue
entry or incrementing the stream count. This will result in stream
count mismatch and future IOMMU attach failures. Such failure can
result in stream on failures in future streams.

Change-Id: I1b3c3ed971348ac58bd90b8833c21bceac9062c8
Signed-off-by: Rajakumar Govindaram <rajakuma@codeaurora.org>