drm/amd/display: Fix DCN compile errors

Fix for DCN compiler errors caused due to various submits

Signed-off-by: Charlene Liu <Charlene.Liu@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c

@@ -1475,6 +1475,8 @@ static void dcn10_pipe_control_lock(
 	struct pipe_ctx *pipe,
 	bool lock)
 {
+	struct mem_input *mi = NULL;
+	mi = dc->res_pool->mis[pipe->pipe_idx];
 	/* use TG master update lock to lock everything on the TG
 	 * therefore only top pipe need to lock
 	 */