iommu/omap: Mark pm functions __maybe_unused

The runtime_pm functions are unused when CONFIG_PM is disabled:

drivers/iommu/omap-iommu.c:1022:12: error: unused function 'omap_iommu_runtime_suspend' [-Werror,-Wunused-function]
static int omap_iommu_runtime_suspend(struct device *dev)
drivers/iommu/omap-iommu.c:1064:12: error: unused function 'omap_iommu_runtime_resume' [-Werror,-Wunused-function]
static int omap_iommu_runtime_resume(struct device *dev)

Mark them as __maybe_unused to let gcc silently drop them
instead of warning.

Fixes: db8918f6 ("iommu/omap: streamline enable/disable through runtime pm callbacks")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/omap-iommu.c

@@ -1019,7 +1019,7 @@ EXPORT_SYMBOL_GPL(omap_iommu_domain_activate);
  * reset line. This function also saves the context of any
  * locked TLBs if suspending.
  **/
-static int omap_iommu_runtime_suspend(struct device *dev)
+static __maybe_unused int omap_iommu_runtime_suspend(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct iommu_platform_data *pdata = dev_get_platdata(dev);
@@ -1061,7 +1061,7 @@ static int omap_iommu_runtime_suspend(struct device *dev)
  * reset line. The function also restores any locked TLBs if
  * resuming after a suspend.
  **/
-static int omap_iommu_runtime_resume(struct device *dev)
+static __maybe_unused int omap_iommu_runtime_resume(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct iommu_platform_data *pdata = dev_get_platdata(dev);