drm/amd/display: Correct updating logic of dcn21's pipe VM flags

[Why]:
Renoir's pipe VM flags are not correctly updated if pipe strategy has
changed during some scenarios. It will result in watermarks mistakenly
calculation, thus underflow and garbage appear.

[How]:
Correctly update pipe VM flags to pipes which have been populated.
Signed-off-by: Dale Zhao <dale.zhao@amd.com>
Signed-off-by: Sung Lee <sung.lee@amd.com>
Reviewed-by: Yongqiang Sun <yongqiang.sun@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c

@@ -1709,12 +1709,8 @@ static int dcn21_populate_dml_pipes_from_context(
 {
 	uint32_t pipe_cnt = dcn20_populate_dml_pipes_from_context(dc, context, pipes);
 	int i;
-	struct resource_context *res_ctx = &context->res_ctx;
 
-	for (i = 0; i < dc->res_pool->pipe_count; i++) {
-
-		if (!res_ctx->pipe_ctx[i].stream)
-			continue;
+	for (i = 0; i < pipe_cnt; i++) {
 
 		pipes[i].pipe.src.hostvm = 1;
 		pipes[i].pipe.src.gpuvm = 1;