iommu/io-pgtable-arm: Use const and __initconst for iommu_gather_ops structures

Check for iommu_gather_ops structures that are only stored in the tlb
field of an io_pgtable_cfg structure. The tlb field is of type
const struct iommu_gather_ops *, so iommu_gather_ops structures
having this property can be declared as const. Also, replace __initdata
with __initconst.
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

drivers/iommu/io-pgtable-arm.c

@@ -916,7 +916,7 @@ static void dummy_tlb_sync(void *cookie)
 	WARN_ON(cookie != cfg_cookie);
 }
 
-static struct iommu_gather_ops dummy_tlb_ops __initdata = {
+static const struct iommu_gather_ops dummy_tlb_ops __initconst = {
 	.tlb_flush_all	= dummy_tlb_flush_all,
 	.tlb_add_flush	= dummy_tlb_add_flush,
 	.tlb_sync	= dummy_tlb_sync,