drm/amdgpu/cgs: always set reference clock in mode_info

It's relevent regardless of whether there are displays
enabled.  Fixes garbage values for ref clock in powerplay
leading to incorrect fan speed reporting when displays
are disabled.

bug: https://bugs.freedesktop.org/show_bug.cgi?id=101653
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/amd/amdgpu/amdgpu_cgs.c

@@ -838,9 +838,12 @@ static int amdgpu_cgs_get_active_displays_info(struct cgs_device *cgs_device,
 		return -EINVAL;
 
 	mode_info = info->mode_info;
-	if (mode_info)
+	if (mode_info) {
 		/* if the displays are off, vblank time is max */
 		mode_info->vblank_time_us = 0xffffffff;
+		/* always set the reference clock */
+		mode_info->ref_clock = adev->clock.spll.reference_freq;
+	}
 
 	if (adev->mode_info.num_crtc && adev->mode_info.mode_config_initialized) {
 		list_for_each_entry(crtc,