[POWERPC] cell: Move PMU-related stuff to include/asm-powerpc/cell-pmu.h

Move some PMU-related macros and function prototypes from cbe_regs.h
and pmu.h in arch/powerpc/platforms/cell/ to a new header at
include/asm-powerpc/cell-pmu.h

This is cleaner to use from the oprofile code, since that sits in
arch/powerpc/oprofile, not in the cell platform directory.

Signed-off-by: Kevin Corry <kevcorry@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>