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/drm_crtc.c

@@ -168,6 +168,7 @@ char *drm_get_encoder_name(struct drm_encoder *encoder)
 		 encoder->base.id);
 	return buf;
 }
+EXPORT_SYMBOL(drm_get_encoder_name);
 
 char *drm_get_connector_name(struct drm_connector *connector)
 {