[POWERPC] cell: Move cbe_regs.h to include/asm-powerpc/cell-regs.h

The new Cell EDAC driver needs that file, oprofile also does ugly
path tricks to get to it, it's time to move it to asm-powerpc. While
at it, rename it to be consistent with cell-pmu.h (and dashes look
nicer than underscores anyway).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>