iommu: add self-consistency tests to ARM LPAE IO page table allocator

This patch adds a series of basic self-consistency tests to the ARM LPAE
IO page table allocator that exercise corner cases in map/unmap, as well
as testing all valid configurations of pagesize, ias and stage.

Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --cc drivers/iommu/Kconfig
Simple merge

diff --cc drivers/iommu/io-pgtable-arm.c
Simple merge