Use OSMO_FD_* instead of deprecated BSC_FD_*

New define is available since libosmocore 1.1.0, and we already require
1.1.0, so no need to update dependenices.
Let's change it to avoid people re-using old BSC_FD_* symbols when
copy-pasting somewhere else.

Change-Id: I9b6463af713f76c06a144bdbf202c0d91eef4d21
diff --git a/src/libosmo-mgcp/mgcp_network.c b/src/libosmo-mgcp/mgcp_network.c
index cd60ce2..fc15ad2 100644
--- a/src/libosmo-mgcp/mgcp_network.c
+++ b/src/libosmo-mgcp/mgcp_network.c
@@ -1462,7 +1462,7 @@
 	mgcp_set_ip_tos(rtp_end->rtp.fd, cfg->endp_dscp);
 	mgcp_set_ip_tos(rtp_end->rtcp.fd, cfg->endp_dscp);
 
-	rtp_end->rtp.when = BSC_FD_READ;
+	rtp_end->rtp.when = OSMO_FD_READ;
 	if (osmo_fd_register(&rtp_end->rtp) != 0) {
 		LOGPENDP(endp, DRTP, LOGL_ERROR,
 			 "failed to register RTP port %d\n",
@@ -1470,7 +1470,7 @@
 		goto cleanup2;
 	}
 
-	rtp_end->rtcp.when = BSC_FD_READ;
+	rtp_end->rtcp.when = OSMO_FD_READ;
 	if (osmo_fd_register(&rtp_end->rtcp) != 0) {
 		LOGPENDP(endp, DRTP, LOGL_ERROR,
 			 "failed to register RTCP port %d\n",