netfilter: xt_qtaguid: extend iface stat to report protocols

In the past the iface_stat_fmt would only show global bytes/packets
for the skb-based numbers.
For stall detection in userspace, distinguishing tcp vs other protocols
makes it easier.
Now we report
  ifname total_skb_rx_bytes total_skb_rx_packets total_skb_tx_bytes
  total_skb_tx_packets {rx,tx}_{tcp,udp,ohter}_{bytes,packets}

Bug: 6818637

CRs-Fixed: 509089 511633
Change-Id: I06b91826d142fda8444aa6ebe3d0efd6a0a1ce8b
Signed-off-by: JP Abgrall <jpa@google.com>
Git-commit: 01d1733e27c7c03dc700cd8cd7658b326bc0b1b2
Git-repo: https://android.googlesource.com/kernel/common/
Signed-off-by: Sridhar Gujje <sgujje@codeaurora.org>