init/calibrate.c: fix for critical bogoMIPS intermittent calculation failure

A fix to the TSC (Time Stamp Counter) based bogoMIPS calculation used on
secondary CPUs which has two faults:

1: Not handling wrapping of the lower 32 bits of the TSC counter on
   32bit kernel - perhaps TSC is not reset by a warm reset?

2: TSC and Jiffies are no incrementing together properly.  Either
   jiffies increment too quickly or Time Stamp Counter isn't incremented
   in during an SMI but the real time clock is and jiffies are
   incremented.

Case 1 can result in a factor of 16 too large a value which makes udelay()
values too small and can cause mysterious driver errors.  Case 2 appears
to give smaller 10-15% errors after averaging but enough to cause
occasional failures on my own board

I have tested this code on my own branch and attach patch suitable for
current kernel code.  See below for examples of the failures and how the
fix handles these situations now.

I reported this issue earlier here:
     Intermittent ...