oml: Fix premature Opstart to Radio Carrier

During the A-bis/OML bootstrapping, osmo-bsc sends Opstart to the
Radio Carrier MO twice.  The first Opstart is triggered by the
State Changed Event Report, originated by the Radio Carrier itself.
The second is triggered by Software Activated Report.

According to 3GPP TS 12.21, figure 2, we shall send it only once,
after the "Attribute setting" step.  Therefore, the first Opstart
is premature, and we shall not send it.

Related: SYS#5063, OS#4755
Change-Id: If69393551117266ecb726d8961153560b2b3cc59
diff --git a/include/osmocom/bsc/signal.h b/include/osmocom/bsc/signal.h
index 952e03c..c7d7fe1 100644
--- a/include/osmocom/bsc/signal.h
+++ b/include/osmocom/bsc/signal.h
@@ -73,6 +73,7 @@
 	S_NM_OM2K_CONF_RES,	/* OM2K Configuration Result */
 	S_NM_OPSTART_ACK,	/* Received OPSTART ACK, arg is struct msgb *oml_msg */
 	S_NM_GET_ATTR_REP,	/* Received Get Attributes Response, arg is struct msgb *oml_msg */
+	S_NM_SET_RADIO_ATTR_ACK, /* Received Set Radio Carrier Attributes Ack, arg is struct msgb *oml_msg */
 };
 
 /* SS_LCHAN signals */