Since r289279 bufinit() uses mp_ncpus so adapt to what x86 does and
set this variable already in cpu_mp_setmaxid().
While at it, rename cpu_cpuid_prop() to cpu_portid_prop() as well as
the MD cpuid variable to portid to avoid confusion with the MI use
of "cpuid" and make some variable static/global in order to reduce
stack usage.
PR: 204685
5101cb4efc