fbdev: move FBIO_WAITFORVSYNC to linux/fb.h

FBIO_WAITFORVSYNC is currently implemented by matroxfb, atyfb, intelfb and
more.  All of them keep redefining the same FBIO_WAITFORVSYNC macro over
and over again, so move it to linux/fb.h and clean up those duplicate
defines.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Cc: Ville Syrjala <syrjala@sci.fi>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Maik Broemme <mbroemme@plusserver.de>
Cc: Petr Vandrovec <vandrove@vc.cvut.cz>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: "Hiremath, Vaibhav" <hvaibhav@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>