iommu/arm: Remove arch_iommu_populate_page_table() completely

The Arm realization should have been removed in the following commit
as redundant:
f89f555 remove late (on-demand) construction of IOMMU page tables

So, remove unused function completely.

Fixes: f89f555 ('remove late (on-demand) construction of IOMMU page tables')
Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Release-acked-by: Juergen Gross <jgross@suse.com>

xen/drivers/passthrough/arm/iommu.c

@@ -132,12 +132,6 @@ void arch_iommu_domain_destroy(struct domain *d)
 {
 }
 
-int arch_iommu_populate_page_table(struct domain *d)
-{
-    /* The IOMMU shares the p2m with the CPU */
-    return -ENOSYS;
-}
-
 void __hwdom_init arch_iommu_hwdom_init(struct domain *d)
 {
 }