[POWERPC] Oprofile cleanup

Clean up the ctr_read/write a bit. It's currently defined in the
include but only used in one C file each. The only exception is the
classic version, so keep that in the include and define in the C file
as appropriate.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>