drm/gf119-/disp: fix nasty bug which can clobber SOR0's clock setup

Fixes a LVDS bleed issue on Lenovo W530 that can occur under a
number of circumstances.

Cc: <stable@vger.kernel.org > # v3.9+
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/core/engine/disp/nvd0.c

@@ -1009,7 +1009,7 @@ exec_clkcmp(struct nv50_disp_priv *priv, int head, int id,
 	}
 
 	if (outp == 8)
-		return false;
+		return conf;
 
 	data = exec_lookup(priv, head, outp, ctrl, dcb, &ver, &hdr, &cnt, &len, &info1);
 	if (data == 0x0000)