vt: remove 25 years stale comment

vc_cons was made global (non-static) in 1.3.38, almost 25 years ago.
Remove a comment which says that it would be a disadvantage to do so :P.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200615074910.19267-7-jslaby@suse.cz


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>