BACKPORT: FROMLIST: iommu/io-pgtable-arm: Prepare PTE methods for handling multiple entries

The PTE methods currently operate on a single entry. In preparation
for manipulating multiple PTEs in one map or unmap call, allow them
to handle multiple PTEs.

Bug: 178537788
Change-Id: I6c7b240b416a876400dc01d7852125652c0e9e8a
Link: https://lore.kernel.org/linux-iommu/20210408171402.12607-1-isaacm@codeaurora.org/T/#t


Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
Suggested-by: Robin Murphy <robin.murphy@arm.com>