bus: ti-sysc: mark PM functions as __maybe_unused

The new bus driver causes a harmless compile-time warning when
CONFIG_PM is disabled:

drivers/bus/ti-sysc.c:440:12: error: 'sysc_runtime_resume' defined but not used [-Werror=unused-function]
 static int sysc_runtime_resume(struct device *dev)
            ^~~~~~~~~~~~~~~~~~~
drivers/bus/ti-sysc.c:421:12: error: 'sysc_runtime_suspend' defined but not used [-Werror=unused-function]
 static int sysc_runtime_suspend(struct device *dev)
            ^~~~~~~~~~~~~~~~~~~~

This marks the two unused functions as __maybe_unused to shut up
that warning.

Fixes: 0eecc636e5 ("bus: ti-sysc: Add minimal TI sysc interconnect target driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/bus/ti-sysc.c

@@ -418,7 +418,7 @@ static void sysc_show_registers(struct sysc *ddata)
 		buf);
 }
 
-static int sysc_runtime_suspend(struct device *dev)
+static int __maybe_unused sysc_runtime_suspend(struct device *dev)
 {
 	struct sysc *ddata;
 	int i;
@@ -437,7 +437,7 @@ static int sysc_runtime_suspend(struct device *dev)
 	return 0;
 }
 
-static int sysc_runtime_resume(struct device *dev)
+static int __maybe_unused sysc_runtime_resume(struct device *dev)
 {
 	struct sysc *ddata;
 	int i, error;