iommu/of: Support ats-supported device-tree property

Device-tree declares whether a PCI root-complex supports ATS by setting
the "ats-supported" property. Copy this flag into device fwspec to let
IOMMU drivers quickly check if they can enable ATS for a device.

Tested-by: Ketan Patil <ketanp@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20240607105415.2501934-4-jean-philippe@linaro.org


Signed-off-by: Will Deacon <will@kernel.org>