f_flower: implement pfcp opts

f_flower: implement pfcp opts

Allow adding tc filter for PFCP header.

Add support for parsing TCA_FLOWER_KEY_ENC_OPTS_PFCP.
Options are as follows: TYPE:SEID.

TYPE is a 8-bit value represented in hex and can be  1
for session header and 0 for node header. In PFCP packet
this is S flag in header.

SEID is a 64-bit session id value represented in hex.

This patch enables adding hardware filters using PFCP fields, see [1].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=d823265dd45bbf14bd67aa476057108feb4143ce

Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Signed-off-by: David Ahern <dsahern@kernel.org>