freebsd compat: Updates and additions for a newer iflib.

freebsd_network: Add a missed method ID.

Some less-used drivers (e.g. marvell_yukon) need this.

freebsd_network: Add an "id" field to struct device_method.

"const char* name" is alright for the compat layer's needs to
identify functions, as we only scan the method table once and
copy the function pointers to a struct of function pointers.

iflib doesn't use a function pointer struct, though, and expects
to have the KOBJ system for function lookups, and that depends
on integer-based method IDs for fast lookups. So now every
method gets an integer ID as well as a name (and iflib's method
IDs are in the list of method IDs already.)