memory: tegra: mark PM functions as __maybe_unused

Without this, we get a couple of warnings when CONFIG_PM_SLEEP is disabled.

../drivers/memory/tegra/tegra186.c:1578:12: warning: ‘tegra186_mc_resume’ defined but not used [-Wunused-function]
1578 | static int tegra186_mc_resume(struct device *dev)

      |            ^~~~~~~~~~~~~~~~~~
../drivers/memory/tegra/tegra186.c:1573:12: warning: ‘tegra186_mc_suspend’ defined but not used [-Wunused-function]
 1573 | static int tegra186_mc_suspend(struct device *dev)
      |            ^~~~~~~~~~~~~~~~~~~

---
 drivers/memory/tegra/tegra186.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index 5d53f11ca7b6..e25c954dde2e 100644
@@ -1570,12 +1570,12 @@ static const struct of_device_id tegra186_mc_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, tegra186_mc_of_match);
 
-static int tegra186_mc_suspend(struct device *dev)
+static int __maybe_unused tegra186_mc_suspend(struct device *dev)
 {
 	return 0;
 }
 
-static int tegra186_mc_resume(struct device *dev)
+static int __maybe_unused tegra186_mc_resume(struct device *dev)
 {
 	struct tegra186_mc *mc = dev_get_drvdata(dev);
 

2.20.1