Revert "Add vp9_highbitdepth info in configure --help"

This reverts commit a6715a75589b418f9af5f44d93e0d7ecbaa77d48.

Removes a duplicate entry; this was previously added by:
14e37cf Add help info for --enable-vp9-highbitdepth

Change-Id: I61408e782232821ef6ed84775b5c79d172ba7f2d
1 file changed