lantiq: remove dummy ltq_machine_power_off to fix gpio-poweroff drivers

Signed-off-by: Felix Fietkau <nbd@nbd.name>

target/linux/lantiq/patches-4.4/0047-poweroff.patch

@@ -0,0 +1,23 @@
+--- a/arch/mips/lantiq/xway/reset.c
++++ b/arch/mips/lantiq/xway/reset.c
+@@ -301,12 +301,6 @@ static void ltq_machine_halt(void)
+ 	unreachable();
+ }
+ 
+-static void ltq_machine_power_off(void)
+-{
+-	local_irq_disable();
+-	unreachable();
+-}
+-
+ static void ltq_usb_init(void)
+ {
+ 	/* Power for USB cores 1 & 2 */
+@@ -379,7 +373,6 @@ static int __init mips_reboot_setup(void
+ 
+ 	_machine_restart = ltq_machine_restart;
+ 	_machine_halt = ltq_machine_halt;
+-	pm_power_off = ltq_machine_power_off;
+ 
+ 	return 0;
+ }