sgsn: when receiving data PDU notify the Gb GMM fsm

When receiving a PDU, the GMM fsm will change to state MM_READY
and will re-arm the T3314

Relates: OS#1941
Change-Id: I78f40762fb17bbd4a6f35608a793f8e5271e9b86
diff --git a/include/osmocom/sgsn/gprs_gb.h b/include/osmocom/sgsn/gprs_gb.h
index 3bc3676..47f2a31 100644
--- a/include/osmocom/sgsn/gprs_gb.h
+++ b/include/osmocom/sgsn/gprs_gb.h
@@ -3,7 +3,9 @@
 #include <stdbool.h>
 
 #include <osmocom/core/msgb.h>
-#include <osmocom/sgsn/gprs_rllc.h>
+#include <osmocom/sgsn/gprs_llc.h>
 
 int gsm0408_gprs_rcvmsg_gb(struct msgb *msg, struct gprs_llc_llme *llme,
 			   bool drop_cipherable);
+/* Has to be called whenever any PDU (signaling, data, ...) has been received */
+void gprs_gb_recv_pdu(struct sgsn_mm_ctx *mmctx);