iommu: Init iommu-groups support earlier, in core_initcall

iommu_group_alloc might be called very early in case of iommu controllers
activated from of_iommu, so ensure that this part of subsystem is ready
when devices are being populated from device-tree (core_initcall seems to
be okay for this case).
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -1207,7 +1207,7 @@ static int __init iommu_init(void)
 
 	return 0;
 }
-arch_initcall(iommu_init);
+core_initcall(iommu_init);
 
 int iommu_domain_get_attr(struct iommu_domain *domain,
 			  enum iommu_attr attr, void *data)