[POWERPC] Oprofile support for Power 5++

This adds a new oprofile cpu type for Power 5 revision 3 chips.
The new name is ppc64/power5++ and is used so that the performance
counters can be set up correctly.

Signed-off-by: Mike Wolf <mjw@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>