drm/amd/display: Toggle VSR button cause system crash

[Why]
in dcn10_apply_ctx_for_surface(), if we hit !top_pipe_to_program,
pipe_ctx->update_flags could not get cleared.

[How]
Moved clearing pipe_ctx->update_flags logic before if
(!top_pipe_to_program) to gurantee pipe_ctx->update_flags get cleared.

Signed-off-by: Peikang Zhang <peikang.zhang@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>