sgsn: Fill the cch_pdp with a value coming from the tlv structure

For some GGSNs we need to insert the PDP Charging Characteristics
that were returned. We receive these values from GSUP and will
fill them into the tlv structure when finding the ggsn context.

Change-Id: I1725bfd2403d29ce3550bfcd6fcc1498426ef906
diff --git a/include/openbsc/gprs_sgsn.h b/include/openbsc/gprs_sgsn.h
index fd86174..4e49c08 100644
--- a/include/openbsc/gprs_sgsn.h
+++ b/include/openbsc/gprs_sgsn.h
@@ -393,6 +393,8 @@
 	char			apn_str[GSM_APN_LENGTH];
 	uint8_t			qos_subscribed[20];
 	size_t			qos_subscribed_len;
+	uint8_t			pdp_charg[2];
+	bool			has_pdp_charg;
 };
 
 struct sgsn_subscriber_data {
@@ -407,6 +409,9 @@
 
 	uint8_t			hlr[9];
 	size_t			hlr_len;
+
+	uint8_t			pdp_charg[2];
+	bool			has_pdp_charg;
 };
 
 #define SGSN_ERROR_CAUSE_NONE (-1)