[PATCH v2 net-next] wireguard: allowedips: Add WGALLOWEDIP_F_REMOVE_ME flag

[Jordan Rife]

> Better still use NLA_POLICY_MASK() so that nla_parse_nested() can
> perform the validation and attach a machine readable info about
> the failure.

This is definitely cleaner for the new WGALLOWEDIP_A_FLAGS parameter.
Thanks for the suggestion.

Applying this to WGPEER_A_FLAGS would simplify the existing validation
logic as well, although I think it changes the error code returned if
a user provides an invalid flag from EOPNOTSUPP to EINVAL. I'm not
sure if there's anything relying on this behavior. I'll let Jason make
the final call there.

-Jordan