Fix the CPU timer and clock comparator output for the "bt -a" command
on S390X machines.  The output of CPU timer and clock comparator has
always been incorrect because:
  - We added S390X_WORD_SIZE (8) instead of 4 to get the second word
  - We did not left shift the clock comparator by 8
The fix gets the complete 64 bit values and by shifting the clock
comparator correctly.
(holzheu@linux.vnet.ibm.com)