input/demux: remove legacy comment that is no longer relevant
input/demux: remove legacy comment that is no longer relevant

The comment in question was first introduced in 47d4e67, and back then
the code that followed looked very different.

Given that the code has evolved and no longer do what the comment is
stating, the comment is removed by this commit.

Signed-off-by: Jean-Baptiste Kempf <7b85a41a628204b76aba4326273a3ccc74bd009a@videolan.org>

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc