Update this driver to be more module friendly:

• Dynamically allocate the cpu_softc[] array based on mp_maxid instead of using a statically sized array that depended on 'options SMP'.
• Use mp_maxid rather than MAXCPU when walking all the CPUs looking for a match.
• Always call smp_rendezvous() since UP kernels now provide this.
• Use mp_ncpus rather than cpu_ndevices when determining if we need to disable C3 for SMP machines.

Approved by: re (rwatson)
Reviewed by: njl