viafb: removed duplicated #include's

Removed duplicated #include's in drivers/video/via/global.h.
  debug.h
  viafbdev.h
  viamode.h

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
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>