GSUP: define default GSUP port as 4222

See also:

https://osmocom.org/projects/cellular-infrastructure/wiki/Port_Numbers

https://gerrit.osmocom.org/#/c/3195/2/include/openbsc/osmo_msc.h@13
(change-id I639544a6cdda77a3aafc4e3446a55393f60e4050)

Change-Id: I4222e21686c823985be8ff1f16b1182be8ad6175
diff --git a/include/osmocom/gsm/gsup.h b/include/osmocom/gsm/gsup.h
index 890bff3..36e5c84 100644
--- a/include/osmocom/gsm/gsup.h
+++ b/include/osmocom/gsm/gsup.h
@@ -27,6 +27,8 @@
 #include <osmocom/gsm/protocol/gsm_04_08_gprs.h>
 #include <osmocom/crypt/auth.h>
 
+#define OSMO_GSUP_PORT 4222
+
 /*! Maximum nubmer of PDP inside \ref osmo_gsup_message */
 #define OSMO_GSUP_MAX_NUM_PDP_INFO		10 /* GSM 09.02 limits this to 50 */
 /*! Maximum number of auth info inside \ref osmo_gsup_message */