PS3 save power on halt:
  - Replace infinite busy loops by smarter loops calling
    lv1_pause() to save power.
  - Add ps3_halt() and ps3_sys_manager_halt().
  - Add __noreturn annotations.
Signed-off-by: NGeert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: NGeoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>