bs11_config: makes sure we disconnect properly before exiting

diff --git a/src/rs232.c b/src/rs232.c
index 90e8818..92e2e9b 100644
--- a/src/rs232.c
+++ b/src/rs232.c
@@ -50,6 +50,8 @@
 
 #define LAPD_HDR_LEN	10
 
+static int handle_ser_write(struct bsc_fd *bfd);
+
 /* callback from abis_nm */
 int _abis_nm_sendmsg(struct msgb *msg)
 {
@@ -78,6 +80,9 @@
 	msgb_enqueue(&sh->tx_queue, msg);
 	sh->fd.when |= BSC_FD_WRITE;
 
+	/* we try to immediately send */
+	handle_ser_write(&sh->fd);
+
 	return 0;
 }