gsup: Specify the QoS service for the PDP info

QoS is a mess. In MAP there is qos-Subscribed which is then extended
using ext-QoS-Subscribed, ext2-QoS-Subscribed, ext3-QoS-Subscribed
and maybe even ext4-QoS-Subscribed by now. The MAP ASN1 files defined
how these need to be "linearized". Instead of copying this I have
decided to include the two semantics with/without the Allocation/Retention
policy using the size of the data.
diff --git a/openbsc/doc/sgsn-remote-protocol.txt b/openbsc/doc/sgsn-remote-protocol.txt
index 27b9abf..acb24a5 100644
--- a/openbsc/doc/sgsn-remote-protocol.txt
+++ b/openbsc/doc/sgsn-remote-protocol.txt
@@ -280,6 +280,7 @@
   10	PDP context id		big endian int, 1-N 	C	TLV	3
   11	PDP type		4.2.4			C	TLV	4
   12	Access point name	04.08, 10.5.6.1		C	TLV	3-102
+  13	Quality of Service	4.2.11			O	TLV	1-20
 
 The conditional IE are mandantory unless mentioned otherwise.
 
@@ -359,6 +360,7 @@
   | 0x10   PDP context id big endian int                    |
   | 0x11   PDP type       4.2.4                             |
   | 0x12   APN            04.08, 10.5.6.1                   |
+  | 0x13   QoS            4.2.11                            |
   | 0x20   RAND           octet string                      |
   | 0x21   SRES           octet string                      |
   | 0x22   Kc             octet string                      |
@@ -420,3 +422,23 @@
   +-----------------------------------------------------+
   :                                                     :   :
   +-----------------------------------------------------+
+
+
+4.2.11 Quality of Service Subscribed Service
+
+This encodes the subscribed QoS of a subscriber. It will be used by the
+SGSN during the PDP Context activation. If the length of the QoS data
+is 3 (three) octets it is assumed that these are octets 3-5 of the TS
+3GPP TS 24.008 Quality of Service Octets. If it is more than three then
+then it is assumed that the first octet is the Allocation/Retention
+Priority and the reset are encoded as octets 3-N of 24.008.
+
+
+     8      7      6      5      4      3      2      1
+  +-----------------------------------------------------+
+  |     |  IEI                                          | octet 1
+  +-----------------------------------------------------+
+  |   Length of IE contents                             | octet 2
+  +-----------------------------------------------------+
+  :                                                     :   :
+  +-----------------------------------------------------+