drm/amd/display: fix struct init in update_bounding_box

dcn20_resource.c:2636:9: error: missing braces around initializer [-Werror=missing-braces]
  struct _vcs_dpi_voltage_scaling_st calculated_states[MAX_CLOCK_LIMIT_STATES] = {0};
         ^

Fixes: 7ed4e635 ("drm/amd/display: Add DCN2 HW Sequencer and Resource")

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>