drm/kms_helper: Add a common place to call init and exit functions.

drm/kms_helper: Add a common place to call init and exit functions.

BugLink: http://bugs.launchpad.net/bugs/1599109
The module_init and module_exit functions will start here, and call the
subsequent init's and exit's.

v10:
 - Keep __init on drm_fb_helper init function.
 - Move MODULE_* macros to the common file.

Signed-off-by: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1453417821-2811-2-git-send-email-rafael.antognolli@intel.com
(cherry picked from commit 70412cfa6ddebcc01e6b01b3fccb6068e48596ac)
Signed-off-by: Timo Aaltonen <timo.aaltonen@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>