Fix edge cases in several KASSERTs: use <= rather than < when testing that
counters have not gone about MAXCPU or NETISR_MAXPROT. These problems
caused panics on UP kernels with INVARIANTS when using sysctl -a, but
would also have caused problems for 32-core boxes or if the netisr
protocol vector was fully populated.

Reported by: nwhitehorn, Neel Natu <neelnatu@gmail.com>
MFC after: 4 days