media: omap: omap-iommu.h: allow building drivers with COMPILE_TEST

Drivers that depend on omap-iommu.h (currently, just omap3isp)
need a stub implementation in order to be built with COMPILE_TEST.
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

include/linux/omap-iommu.h

@@ -13,7 +13,12 @@
 #ifndef _OMAP_IOMMU_H_
 #define _OMAP_IOMMU_H_
 
+#ifdef CONFIG_OMAP_IOMMU
 extern void omap_iommu_save_ctx(struct device *dev);
 extern void omap_iommu_restore_ctx(struct device *dev);
+#else
+static inline void omap_iommu_save_ctx(struct device *dev) {}
+static inline void omap_iommu_restore_ctx(struct device *dev) {}
+#endif
 
 #endif