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

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

drivers/gpu/drm/Makefile

@@ -22,7 +22,9 @@ drm-$(CONFIG_OF) += drm_of.o
 drm-$(CONFIG_AGP) += drm_agpsupport.o
 
 drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \
-		drm_plane_helper.o drm_dp_mst_topology.o drm_atomic_helper.o
+		drm_plane_helper.o drm_dp_mst_topology.o drm_atomic_helper.o \
+		drm_kms_helper_common.o
+
 drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
 drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
 drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o