drm/tinydrm: Remove explicit .best_encoder assignment

Since the driver is relying on the atomic helpers, remove the explicit
.best_encoder assignment and let the core call
drm_atomic_helper_best_encoder().

Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20171010205858.GA4806@Haneen

drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c

@@ -51,7 +51,6 @@ static int tinydrm_connector_get_modes(struct drm_connector *connector)
 
 static const struct drm_connector_helper_funcs tinydrm_connector_hfuncs = {
 	.get_modes = tinydrm_connector_get_modes,
-	.best_encoder = drm_atomic_helper_best_encoder,
 };
 
 static enum drm_connector_status