drm/i915: Only print "nothing to do" debug message as required.

If the FBC is already disabled, then we do not even attempt to disable
FBC and so there is no point emitting a debug statement at that point,
having already emitted one saying why we are disabling FBC.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NEric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/intel_display.c

@@ -1248,10 +1248,11 @@ static void intel_update_fbc(struct drm_crtc *crtc,
 	return;
 
 out_disable:
-	DRM_DEBUG_KMS("unsupported config, disabling FBC\n");
 	/* Multiple disables should be harmless */
-	if (intel_fbc_enabled(dev))
+	if (intel_fbc_enabled(dev)) {
+		DRM_DEBUG_KMS("unsupported config, disabling FBC\n");
 		intel_disable_fbc(dev);
+	}
 }
 
 static int