viafb: remove dead code due to IGA1_IGA2

Some code depended on IGA1_IGA2 which was never set (at least with the
symbolic name).  Remove this dead code although it might one day be useful
to get a hint on how some things might work.  However as this is dead it
is likely full of bugs and would prevent a clean structure (as it has some
very strange things).

Dead code -> no regressions, at least if VIA doesn't do anything very ugly.

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