drm/mode_object: Export drm_mode_obj_find_prop_id for tests

We'll need to use drm_mode_obj_find_prop_id() for kunit tests to make
sure a given property has been properly created. Let's export it for
tests only.
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240527-kms-hdmi-connector-state-v15-5-c5af16c3aae2@kernel.orgSigned-off-by: Maxime Ripard <mripard@kernel.org>

drivers/gpu/drm/drm_mode_object.c

@@ -478,6 +478,7 @@ struct drm_property *drm_mode_obj_find_prop_id(struct drm_mode_object *obj,
 
 	return NULL;
 }
+EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_mode_obj_find_prop_id);
 
 static int set_property_legacy(struct drm_mode_object *obj,
 			       struct drm_property *prop,