VTY: Don't display 'PDP Address: invalid' for IPv4v6

We were not handling the case of PDP_TYPE_N_IETF_IPv4v6
in gprs_pdpaddr2str() and showed "invalid" for these addresses.

Depends: libosmocore Change-Id: I1f82f9d8fc13dcc4474760329bd74ae9685b9031
Change-Id: Id36b7520677e4a0af40d05dc503b26d1b0b74a26
diff --git a/include/osmocom/sgsn/gprs_sgsn.h b/include/osmocom/sgsn/gprs_sgsn.h
index c176494..dcda5c3 100644
--- a/include/osmocom/sgsn/gprs_sgsn.h
+++ b/include/osmocom/sgsn/gprs_sgsn.h
@@ -417,7 +417,7 @@
 struct sgsn_instance *sgsn_instance_alloc(void *talloc_ctx);
 void sgsn_inst_init(struct sgsn_instance *sgsn);
 
-char *gprs_pdpaddr2str(uint8_t *pdpa, uint8_t len);
+char *gprs_pdpaddr2str(uint8_t *pdpa, uint8_t len, bool return_ipv6);
 
 /*
  * ctrl interface related work