osmux: remove redundant log message when bsc doesn't want to use Osmux

Remove redundant information log message:

<000b> bsc_mgcp_utils.c:647 BSC doesn't want to use Osmux, failing back to RTP
<000b> bsc_mgcp_utils.c:669 bsc didn't accept to use Osmux (cid=0)

One single log message is just fine. The error path already indicates
the precise reason not to accept the request to use Osmux.
diff --git a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
index 606ac92..d580397 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
@@ -654,7 +654,7 @@
 	}
 
 	if (endp->osmux.cid != osmux_cid) {
-		LOGP(DMGCP, LOGL_INFO,
+		LOGP(DMGCP, LOGL_ERROR,
 		     "BSC sent us wrong CID %u, we expected %u",
 		     osmux_cid, endp->osmux.cid);
 		goto err;
@@ -664,8 +664,6 @@
 	     osmux_cid);
 	return;
 err:
-	LOGP(DMGCP, LOGL_NOTICE, "bsc didn't accept to use Osmux (cid=%u)\n",
-	     osmux_cid);
 	osmux_put_cid(endp->osmux.cid);
 	endp->osmux.cid = -1;
 	endp->osmux.state = OSMUX_STATE_DISABLED;