ip: ipstats: Iterate all xstats attributes

ip: ipstats: Iterate all xstats attributes

ipstats_stat_desc_show_xstats() operates by first parsing the attribute
stream into a type-indexed table, and then accessing the right attribute.
But bridge VLAN stats are given as several BRIDGE_XSTATS_VLAN attributes,
one per VLAN. With the above approach to parsing, only one of these
attributes would be shown. Instead, iterate the stream of attributes and
call the show_cb for each one with a matching type.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David Ahern <dsahern@kernel.org>