lavfi/mp: remove mp=tinterlace wrapper

From various tests, there is no evidence that the filter is faster than
the native tinterlace, and it has several more limitations and a few
bugs.

See thread:
Subject: [FFmpeg-devel] [NOPATCH] lavfi/mp: drop tinterlace wrapper
Date: Wed, 5 Sep 2012 00:26:01 +0200
