viafb: deprecate private ioctls

Print a warning when viafb ioctls are called.  Those should not be used as
their exact meaning is sometimes unknown and they in parts duplicate
functionality present in the framebuffer interface.

There is no known user of these ioctls.

Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Joseph Chan <JosephChan@via.com.tw>
Cc: Scott Fang <ScottFang@viatech.com.cn>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>