[MIPS] Export pm_power_off

This is required for ipmi_poweroff.c to work as a module.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/reset.c

@@ -23,6 +23,8 @@ void (*_machine_restart)(char *command);
 void (*_machine_halt)(void);
 void (*pm_power_off)(void);
 
+EXPORT_SYMBOL(pm_power_off);
+
 void machine_restart(char *command)
 {
 	if (_machine_restart)