drm/fb: fix fbdev object model + cleanup properly.

The fbdev layer in the kms code should act like a consumer of the kms services and avoid having relying on information being store in the kms core structures in order for it to work.

This patch

a) removes the info pointer/psuedo palette from the core drm_framebuffer structure and moves it to the fbdev helper layer, it also removes the core drm keeping a list of kernel kms fbdevs.
b) migrated all the fb helper functions out of the crtc helper file into the fb helper file.
c) pushed the fb probing/hotplug control into the driver
d) makes the surface sizes into a structure for ease of passing
This changes the intel/radeon/nouveau drivers to use the new helper.

Signed-off-by: Dave Airlie <airlied@redhat.com>