viafb: remove unused video device stuff

Remove everything related to video devices from the driver as it did not
influence the driver operation.  This patch does change the userspace
behaviour as it removes two IOCTLs and one module parameter.  But this is
good as it removes useless stuff and helps the user to figure out the
options that do affect the driver behaviour (which are still too many).

Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Scott Fang <ScottFang@viatech.com.cn>
Cc: Joseph Chan <JosephChan@via.com.tw>
Cc: Harald Welte <laforge@gnumonks.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>