src: use namespace prefix osmo_timer* for timer functions

Summary of changes:

s/struct timer_list/struct osmo_timer_list/g
s/bsc_add_timer/osmo_timer_add/g
s/bsc_schedule_timer/osmo_timer_schedule/g
s/bsc_del_timer/osmo_timer_del/g
s/bsc_timer_pending/osmo_timer_pending/g
s/bsc_nearest_timer/osmo_timers_nearest/g
s/bsc_prepare_timers/osmo_timers_prepare/g
s/bsc_update_timers/osmo_timers_update/g
s/bsc_timer_check/osmo_timers_check/g
diff --git a/openbsc/src/libbsc/bsc_api.c b/openbsc/src/libbsc/bsc_api.c
index 4b48ec6..09e9de4 100644
--- a/openbsc/src/libbsc/bsc_api.c
+++ b/openbsc/src/libbsc/bsc_api.c
@@ -325,7 +325,7 @@
 	/* we will now start the timer to complete the assignment */
 	conn->T10.cb = assignment_t10_timeout;
 	conn->T10.data = conn;
-	bsc_schedule_timer(&conn->T10, GSM0808_T10_VALUE);
+	osmo_timer_schedule(&conn->T10, GSM0808_T10_VALUE);
 	return 0;
 
 error:
@@ -358,7 +358,7 @@
 	}
 
 	/* swap channels */
-	bsc_del_timer(&conn->T10);
+	osmo_timer_del(&conn->T10);
 
 	lchan_release(conn->lchan, 0, 1);
 	conn->lchan = conn->secondary_lchan;
@@ -387,7 +387,7 @@
 	}
 
 	/* stop the timer and release it */
-	bsc_del_timer(&conn->T10);
+	osmo_timer_del(&conn->T10);
 	lchan_release(conn->secondary_lchan, 0, 1);
 	conn->secondary_lchan = NULL;
 
@@ -435,7 +435,7 @@
 			handle_ass_fail(conn, msg);
 			break;
 		case GSM48_MT_RR_CHAN_MODE_MODIF_ACK:
-			bsc_del_timer(&conn->T10);
+			osmo_timer_del(&conn->T10);
 			rc = gsm48_rx_rr_modif_ack(msg);
 			if (rc < 0 && api->assign_fail) {
 				api->assign_fail(conn,
@@ -536,7 +536,7 @@
 	conn->ho_lchan = NULL;
 	conn->bts = NULL;
 
-	bsc_del_timer(&conn->T10);
+	osmo_timer_del(&conn->T10);
 
 	return 0;
 }
@@ -621,7 +621,7 @@
 	int destruct = 1;
 
 	if (conn->secondary_lchan == lchan) {
-		bsc_del_timer(&conn->T10);
+		osmo_timer_del(&conn->T10);
 		conn->secondary_lchan = NULL;
 
 		bsc->assign_fail(conn,