drm/amdgpu: delete duplicated code.

the variable ref_clock was assigned same
value twice in same function.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -948,7 +948,6 @@ static int amdgpu_cgs_get_active_displays_info(struct cgs_device *cgs_device,
 								(amdgpu_crtc->v_border * 2);
 					mode_info->vblank_time_us = vblank_lines * line_time_us;
 					mode_info->refresh_rate = drm_mode_vrefresh(&amdgpu_crtc->hw_mode);
-					mode_info->ref_clock = adev->clock.spll.reference_freq;
 					mode_info = NULL;
 				}
 			}
@@ -958,7 +957,6 @@ static int amdgpu_cgs_get_active_displays_info(struct cgs_device *cgs_device,
 		if (mode_info != NULL) {
 			mode_info->vblank_time_us = adev->pm.pm_display_cfg.min_vblank_time;
 			mode_info->refresh_rate = adev->pm.pm_display_cfg.vrefresh;
-			mode_info->ref_clock = adev->clock.spll.reference_freq;
 		}
 	}
 	return 0;