iommu/arm-smmu: use VA_BITS to determine arm64 virtual address space

With the introduction of the VA_BITS definition for arm64, make use of
it in the driver, allowing up to 42-bits of VA space when configured
with 64k pages.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

drivers/iommu/arm-smmu.c

@@ -24,7 +24,7 @@
  *	- v7/v8 long-descriptor format
  *	- Non-secure access to the SMMU
  *	- 4k and 64k pages, with contiguous pte hints.
- *	- Up to 39-bit addressing
+ *	- Up to 42-bit addressing (dependent on VA_BITS)
  *	- Context fault reporting
  */
 
@@ -1747,7 +1747,6 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
 	 * allocation (PTRS_PER_PGD).
 	 */
 #ifdef CONFIG_64BIT
-	/* Current maximum output size of 39 bits */
 	smmu->s1_output_size = min(39UL, size);
 #else
 	smmu->s1_output_size = min(32UL, size);
@@ -1762,7 +1761,7 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
 	} else {
 #ifdef CONFIG_64BIT
 		size = (id >> ID2_UBS_SHIFT) & ID2_UBS_MASK;
-		size = min(39, arm_smmu_id_size_to_bits(size));
+		size = min(VA_BITS, arm_smmu_id_size_to_bits(size));
 #else
 		size = 32;
 #endif