viafb: returns 0 two too early

Otherwise this will already return 0 if iteration MAXLOOP-2 occurs in the
first loop.

Signed-off-by: Roel Kluin <roel.kluin@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>