bsd: provide correct number of ncpus

As the comment states itself, mp_ncpus should be the number of CPUs
in the system, not the maximum number of CPUs. We can currently grab
that from the smp_processors variable.

I have audited the code for current users, though, and found two places
in which it is used as the maximum number of cpus. Those are changed to
MAXCPU

bsd/porting/netport.h

@@ -252,11 +252,8 @@ static __inline void        splx(intrmask_t ipl)   { return; }
 /* must match max_cpus in include/sched.hh */
 #define MAXCPU		(sizeof(unsigned long) * 8)
 
-/*
- * This should the number of actual, not possible CPUs, but we can't get at
- * that information for now.
- */
-#define mp_ncpus	MAXCPU
+extern unsigned smp_processors;
+#define mp_ncpus smp_processors
 
 /*
  * OSv: Copied from kern_time.c

bsd/sys/cddl/compat/opensolaris/sys/proc.h

@@ -43,8 +43,8 @@
 #define	CPU		curcpu
 #define	minclsyspri	PRIBIO
 #define	maxclsyspri	PVM
-#define	max_ncpus	mp_ncpus
-#define	boot_max_ncpus	mp_ncpus
+#define	max_ncpus	MAXCPU
+#define	boot_max_ncpus	MAXCPU
 
 #define	TS_RUN	0