iommu/io-pgtable-arm: Avoid warning with 32-bit phys_addr_t

It's not entirely unreasonable for io-pgtable-arm to be built for
configurations with 32-bit phys_addr_t, where the compiler rightly
raises a warning about the 36-bit shift. That particular code path
should never actually *run* on those systems, but we still want it
to compile cleanly, which is easily done by using an unambiguous u64
as the intermediate type instead.
Signed-off-by: NRobin Murphy <robin.murphy@arm.com>
Signed-off-by: NJoerg Roedel <jroedel@suse.de>

drivers/iommu/io-pgtable-arm.c

@@ -211,7 +211,7 @@ static arm_lpae_iopte paddr_to_iopte(phys_addr_t paddr,
 static phys_addr_t iopte_to_paddr(arm_lpae_iopte pte,
 				  struct arm_lpae_io_pgtable *data)
 {
-	phys_addr_t paddr = pte & ARM_LPAE_PTE_ADDR_MASK;
+	u64 paddr = pte & ARM_LPAE_PTE_ADDR_MASK;
 
 	if (data->pg_shift < 16)
 		return paddr;