MIPS: ralink: Don't set pm_power_off

Setting pm_power_off is apprently wrong and makes drivers such as
gpio-poweroff not work.
Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11445/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/ralink/reset.c

@@ -98,7 +98,6 @@ static int __init mips_reboot_setup(void)
 {
 	_machine_restart = ralink_restart;
 	_machine_halt = ralink_halt;
-	pm_power_off = ralink_halt;
 
 	return 0;
 }