iommu/core: export iommu_set_fault_handler()

commit 4f3f8d9d "iommu/core: Add fault reporting mechanism" added
the public iommu_set_fault_handler() symbol but forgot to export it.

Fix that.
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

drivers/iommu/iommu.c

@@ -51,6 +51,7 @@ void iommu_set_fault_handler(struct iommu_domain *domain,
 
 	domain->handler = handler;
 }
+EXPORT_SYMBOL_GPL(iommu_set_fault_handler);
 
 struct iommu_domain *iommu_domain_alloc(void)
 {