fbmem, drm/nouveau: kick firmware framebuffers as soon as possible

Currently vesafb/efifb/... is kicked when hardware driver is registering
framebuffer. To do it hardware must be fully functional, so there's a short
window between start of initialisation and framebuffer registration when
two drivers touch the hardware. Unfortunately sometimes it breaks nouveau
initialisation.

Fix it by kicking firmware driver(s) before we start touching the hardware.

Reported-by: Didier Spaier <didier.spaier@epsm.fr>
Tested-by: Didier Spaier <didier.spaier@epsm.fr>
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Peter Jones <pjones@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>