bce(4) with IPMI

[David Christensen]

> Because driver already initialized CPUs and context I thought
> moving bce_pulse() to bce_init() was too late. If that's doable it
> would be more correct way to address this issue.
> 

Moving bce_pulse() is a minimum.  It might be necessary to move
some other code out of bce_attach()/bce_detach() and relocate it 
to bce_init()/bce_stop() so that RX/TX MAC operations aren't 
interrupted.  I've not seen it done that way in other Broadcom 
drivers so I wouldn't expect it to be a trivial effort.

Dave