dco_linux: fix peer stats parsing with new ovpn kernel module

dco_linux: fix peer stats parsing with new ovpn kernel module

The new ovpn kernel module has changed the netlink attribute
type of the fields containing the pkt/bytes counters in the
peer stats.

We moved from uint64 to uint (a dynamic type can be either
32 or 64 bits), therefore the parsing code must be adapted
accordingly.

While at it, also fix the peer object parsing in the P2P code path.

The fix can be verified by enabling --status with verb 6 and
watching the counters increasing:

	2025-05-16 22:23:56 us=649488 dco_get_peer_stats_multi
	2025-05-16 22:23:56 us=651008 dco_parse_peer_multi: parsing message...
	2025-05-16 22:23:56 us=651734 dco_update_peer_stat / dco_read_bytes: 116280
	2025-05-16 22:23:56 us=652682 dco_update_peer_stat / dco_write_bytes: 115776
	2025-05-16 22:23:56 us=653467 dco_update_peer_stat / tun_read_bytes: 90048
	2025-05-16 22:23:56 us=654110 dco_update_peer_stat / tun_write_bytes: 90048

Change-Id: I104b4adeb9f65cce3487b82f35470174acba92bc
Github: closes OpenVPN/openvpn#746
Signed-off-by: Antonio Quartulli <antonio@mandelbit.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20250517083231.27977-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31666.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>