This unifies the code between nla_parse() which sets the bad
attribute pointer and an error message, and nla_validate()
which only sets the bad attribute pointer.
It also cleans up the code for NLA_REJECT and paves the way
for nested policy validation, as it will allow us to easily
skip setting the "generic" message without any extra args
like the **error_msg now, just passing the extack through is
now enough.
While at it, remove the unnecessary label in nla_parse().
Suggested-by: David Ahern <dsahern@gmail.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>