iommu: Make the iova library a module

The iova library has use outside the intel-iommu driver, thus make it a
module.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/iommu/Kconfig

@@ -42,7 +42,7 @@ config IOMMU_IO_PGTABLE_LPAE_SELFTEST
 endmenu
 
 config IOMMU_IOVA
-	bool
+	tristate
 
 config OF_IOMMU
        def_bool y

drivers/iommu/iova.c

@@ -18,6 +18,7 @@
  */
 
 #include <linux/iova.h>
+#include <linux/module.h>
 #include <linux/slab.h>
 
 void
@@ -548,3 +549,6 @@ error:
 		free_iova_mem(prev);
 	return NULL;
 }
+
+MODULE_AUTHOR("Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>");
+MODULE_LICENSE("GPL");