[PATCH] powerpc: Merge ppc64 pmc.[ch] with ppc32 perfmon.[ch]

This patches the ppc32 and ppc64 versions of the headers and .c files
with helper functions for manipulating the performance counting
hardware.  As a side effect, it removes use of the term "perfmon" from
ppc32, thus avoiding confusion with the unrelated performance counter
interface from HP Labs also called "perfmon".

Built, but not booted, for g5, pSeries, iSeries, and 32-bit Powermac
with both ARCH=powerpc and ARCH=ppc{,64} as appropriate.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>