multimedia/vlc: Remove redundant dependencies

Adjust default options so we don't pull in external libraries when
ffmpeg/(lib)avcodec can be used instead.

Deselects following options:
A52, DCA, FAAD, FLAC, MAD and MPEG2

There is no loss in functionality for the user.

PR: 246253
Submitted by: Daniel Engberg <daniel.engberg.lists@pyret.net>