Move sgsn_ctrl_cmds_install() declaration to sgsn.h

sgsn.h is the main header containing all misc app related contents.
This is another step towards shrinking gprs_sgsn.h mess.

Change-Id: I80e3a68e2e368d8c73135c850e4728bdf6cf5f09

include/osmocom/sgsn/gprs_sgsn.h

@@ -296,11 +296,6 @@ extern struct llist_head sgsn_mm_ctxts;
 
 uint32_t sgsn_alloc_ptmsi(void);
 
-/*
- * ctrl interface related work
- */
-int sgsn_ctrl_cmds_install(void);
-
 /*
  * Authorization/ACL handling
  */

include/osmocom/sgsn/sgsn.h

@@ -162,6 +162,11 @@ struct sgsn_instance {
 extern struct sgsn_instance *sgsn;
 extern void *tall_sgsn_ctx;
 
+/*
+ * ctrl interface related work (sgsn_ctrl.c)
+ */
+int sgsn_ctrl_cmds_install(void);
+
 /* sgsn_vty.c */
 
 int sgsn_vty_init(struct sgsn_config *cfg);