In the past only GTPv2C was supported, and had the "gtp" generic prefix.
Later on, GTPv1C support was added, and "gtp1" prefix was used.
Let's move GTPv2C specific bits to have "gtp2" prefix too, and leave
"gtp" prefix for generic stuff among different GTP versions.
* Flow-Description use 'to assigned' in Gx Interface
* Support SDF Filter ID
* Support F-TEID's Choose
* BAR(Buffering) is added in PFCP session
* Default Apply Action uses NOCP|BUFF
<DOWNLINK>
RX : permit out from <P-CSCF_RTP_IP> <P-CSCF_RTP_PORT> to <UE_IP> <UE_PORT>
GX : permit out from <P-CSCF_RTP_IP> <P-CSCF_RTP_PORT> to <UE_IP> <UE_PORT>
PFCP : permit out from <P-CSCF_RTP_IP> <P-CSCF_RTP_PORT> to <UE_IP> <UE_PORT>
RULE : Source <P-CSCF_RTP_IP> <P-CSCF_RTP_PORT> Destination <UE_IP> <UE_PORT>
TFT : Local <UE_IP> <UE_PORT> REMOTE <P-CSCF_RTP_IP> <P-CSCF_RTP_PORT>
<UPLINK>
RX : permit in from <UE_IP> <UE_PORT> to <P-CSCF_RTP_IP> <P-CSCF_RTP_PORT>
GX : permit out from <P-CSCF_RTP_IP> <P-CSCF_RTP_PORT> to <UE_IP> <UE_PORT>
PFCP : permit out from <P-CSCF_RTP_IP> <P-CSCF_RTP_PORT> to <UE_IP> <UE_PORT>
RULE : Source <UE_IP> <UE_PORT> Destination <P-CSCF_RTP_IP> <P-CSCF_RTP_PORT>
TFT : Local <UE_IP> <UE_PORT> REMOTE <P-CSCF_RTP_IP> <P-CSCF_RTP_PORT>