[POWERPC] Fix oprofile support for e500 in arch/powerpc

Fixed a compile error in building the 85xx support with oprofile, and in
the process cleaned up some issues with the fsl_booke performance monitor
code.

* Reorganized FSL Book-E performance monitoring code so that the 7450
  wouldn't be built if the e500 was, and cleaned it up so it was more
  self-contained.

* Added a cpu_setup function for FSL Book-E.  The original
  cpu_setup function prototype had no arguments, assuming that
  the reg_setup function would copy the required information into
  variables which represented the registers.  This was silly for
  e500, since it has 1 register per counter (rather than 3 for
  all counters), so the code has been restructured to have
  cpu_setup take the current counter config array as an argument,
  with op_powerpc_setup() invoking op_powerpc_cpu_setup() through
  on_each_cpu(), and op_powerpc_cpu_setup() invoking the
  model-specific cpu_setup function with an argument.  The
  argument is ignored on all other platforms at present.

* Fixed a confusing line where a trinary operator only had two
  arguments

Signed-off-by: Andrew Fleming <afleming@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>