regarding em and lem

[Barney Cordoba]

Just a programming note, it would be useful for some cases if the 
softc/adapter structures for lem and em were synced with all of the 
common stuff at the top of the structures, so you could access the dev
or hw from the softc without having to know which flavor of driver it
is. Putting non-common stuff at the end is a good programming practice.

It's also not a bad idea to put an identifier in there, such as is_lem,
because it's not easy to figure out naturally.

BC