drm/amd/powerplay/vega10: allow mclk switching with no displays

If there are no displays attached, there is no reason to disable
mclk switching.

Fixes mclks getting set to high when there are no displays attached.
Reviewed-by: NEric Huang <JinhuiEric.Huang@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c

@@ -3171,10 +3171,13 @@ static int vega10_apply_state_adjust_rules(struct pp_hwmgr *hwmgr,
 		PP_CAP(PHM_PlatformCaps_DisableMclkSwitchForVR);
 	force_mclk_high = PP_CAP(PHM_PlatformCaps_ForceMclkHigh);
 
-	disable_mclk_switching = (info.display_count > 1) ||
-				    disable_mclk_switching_for_frame_lock ||
-				    disable_mclk_switching_for_vr ||
-				    force_mclk_high;
+	if (info.display_count == 0)
+		disable_mclk_switching = false;
+	else
+		disable_mclk_switching = (info.display_count > 1) ||
+			disable_mclk_switching_for_frame_lock ||
+			disable_mclk_switching_for_vr ||
+			force_mclk_high;
 
 	sclk = vega10_ps->performance_levels[0].gfx_clock;
 	mclk = vega10_ps->performance_levels[0].mem_clock;