iommu/arm-smmu: Restrict domain attributes to UNMANAGED domains

iommu/arm-smmu: Restrict domain attributes to UNMANAGED domains

The ARM SMMU drivers provide a DOMAIN_ATTR_NESTING domain attribute,
which allows callers of the IOMMU API to request that the page table
for a domain is installed at stage-2, if supported by the hardware.

Since setting this attribute only makes sense for UNMANAGED domains,
this patch returns -ENODEV if the domain_{get,set}_attr operations are
called on other domain types.

BugLink: http://bugs.launchpad.net/bugs/1688158
Signed-off-by: Will Deacon <will.deacon@arm.com>
(cherry picked from commit 0834cc28fa56c65887c614b6c045be2ba06fdcb0)
Signed-off-by: Manoj Iyer <manoj.iyer@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>