drm/radeon: update radeon_atom_is_voltage_gpio() for SI

SI uses a new atom table.  Required for DPM on SI.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/rv6xx_dpm.c b/drivers/gpu/drm/radeon/rv6xx_dpm.c
index e8f07b1..cc2a7c2 100644
--- a/drivers/gpu/drm/radeon/rv6xx_dpm.c
+++ b/drivers/gpu/drm/radeon/rv6xx_dpm.c
@@ -1933,7 +1933,7 @@
 		pi->fb_div_scale = 0;
 
 	pi->voltage_control =
-		radeon_atom_is_voltage_gpio(rdev, SET_VOLTAGE_TYPE_ASIC_VDDC);
+		radeon_atom_is_voltage_gpio(rdev, SET_VOLTAGE_TYPE_ASIC_VDDC, 0);
 
 	pi->gfx_clock_gating = true;