drm/amd/display: remove unused func declaration from resource headers

The function resource_validate_ctx_update_pointer_after_copy() is
declared in resource.h but never defined, therefore, remove its
declaration from headers.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/inc/resource.h

@@ -165,10 +165,6 @@ bool resource_validate_attach_surfaces(
 		struct dc_state *context,
 		const struct resource_pool *pool);
 
-void resource_validate_ctx_update_pointer_after_copy(
-		const struct dc_state *src_ctx,
-		struct dc_state *dst_ctx);
-
 enum dc_status resource_map_clock_resources(
 		const struct dc *dc,
 		struct dc_state *context,