Revert "vp9 svc: fix to make top layer frame non-ref"

Revert "vp9 svc: fix to make top layer frame non-ref"

This reverts commit 254e2f5501d000ca66bc65c5f44bb6a882d4167c.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> vp9 svc: fix to make top layer frame non-ref
>
> Add mismatch check to the datarate test of changing svc pattern on the
> fly.
>
> Change-Id: I6a878736de44e6a40c077ed6430aabd7fadabdd9

TBR=marpan@google.com,builds@webmproject.org,jianj@google.com

Change-Id: Ibcb600438098f8dc380fe7e1de90cb81fc367468
No-Presubmit: true
No-Tree-Checks: true
No-Try: true