net/ice/base: fix GTP-U inner RSS IPv4 IPv6 co-exist

net/ice/base: fix GTP-U inner RSS IPv4 IPv6 co-exist

An IP header combined with GTP-U header should be regarded as
inner layer for RSS, otherwise it mess the field vector between
an IPv4 rule and IPv6 rule e.g:

testpmd> flow create 0 ingress pattern eth / ipv4 / udp / gtpu / \
gtpu_psc  / ipv4 / udp / end actions rss types ipv4-udp end key_len \
0 queues end / end
testpmd> flow create 0 ingress pattern eth / ipv4 / udp / gtpu / \
gtpu_psc  / ipv6 / udp / end actions rss types ipv6-udp end key_len \
0 queues end / end

Fixes: b7d34ccc47b5 ("net/ice/base: packet encapsulation for RSS")
Cc: stable@dpdk.org
Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
Signed-off-by: Junfeng Guo <junfeng.guo@intel.com>
Acked-by: Qiming Yang <qiming.yang@intel.com>