drm: split crtc/fb helpers into a separate module

I really don't want to have core drm module rely on CONFIG_FB,
so this is the easiest answer.

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

drivers/gpu/drm/Makefile

@@ -10,12 +10,15 @@ drm-y       :=	drm_auth.o drm_bufs.o drm_cache.o \
 		drm_lock.o drm_memory.o drm_proc.o drm_stub.o drm_vm.o \
 		drm_agpsupport.o drm_scatter.o ati_pcigart.o drm_pci.o \
 		drm_sysfs.o drm_hashtab.o drm_sman.o drm_mm.o \
-		drm_crtc.o drm_crtc_helper.o drm_modes.o drm_edid.o \
-		drm_info.o drm_debugfs.o drm_encoder_slave.o \
-		drm_fb_helper.o
+		drm_crtc.o drm_modes.o drm_edid.o \
+		drm_info.o drm_debugfs.o drm_encoder_slave.o
 
 drm-$(CONFIG_COMPAT) += drm_ioc32.o
 
+drm_helper-y := drm_fb_helper.o drm_crtc_helper.o
+
+obj-$(CONFIG_DRM_MODE_HELPER) += drm_helper.o
+
 obj-$(CONFIG_DRM)	+= drm.o
 obj-$(CONFIG_DRM_TTM)	+= ttm/
 obj-$(CONFIG_DRM_TDFX)	+= tdfx/