cirrusfb: add __devinit attribute to probing functions

Add __devinit attribute to probing functions.  This fixed section mismatch
warning from my previous patch.

Kill one redundant forward declaration.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>