drm/amdgpu: add missing df counter disable write

Request to stop DF performance counters is missing the actual write to the
controller register.
Reported-by: Chris Freehill <chris.freehill@amd.com>
Signed-off-by: Jonathan Kim <jonathan.kim@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Harish Kasiviswanathan <harish.kasiviswanathan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/df_v3_6.c

@@ -568,6 +568,8 @@ static int df_v3_6_pmc_stop(struct amdgpu_device *adev, uint64_t config,
 		if (ret)
 			return ret;
 
+		df_v3_6_perfmon_wreg(adev, lo_base_addr, lo_val,
+							hi_base_addr, hi_val);
 
 		if (is_remove) {
 			df_v3_6_reset_perfmon_cntr(adev, config, counter_idx);