Restore support for compiling tmiofb with acceleration disabled.

Signed-off-by: Dmitry Baryshkov <dbaryshkov@gmail.com>
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>