net: dsa: Fix build warning for !PM_SLEEP

The dsa_switch_suspend() and dsa_switch_resume() functions are only used
when PM_SLEEP is enabled, so they need #ifdef CONFIG_PM_SLEEP protection
to avoid a compiler warning.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/dsa.c

@@ -238,6 +238,7 @@ static void dsa_switch_destroy(struct dsa_switch *ds)
 {
 }
 
+#ifdef CONFIG_PM_SLEEP
 static int dsa_switch_suspend(struct dsa_switch *ds)
 {
 	int i, ret = 0;
@@ -280,6 +281,7 @@ static int dsa_switch_resume(struct dsa_switch *ds)
 
 	return 0;
 }
+#endif
 
 
 /* link polling *************************************************************/