netlink: re-add parse/validate functions in strict mode

This re-adds the parse and validate functions like nla_parse()
that are now actually strict after the previous rename and were
just split out to make sure everything is converted (and if not
compilation of the previous patch would fail.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>