dt-bindings: Document stall property for IOMMU masters

dt-bindings: Document stall property for IOMMU masters

On ARM systems, some platform devices behind an IOMMU may support stall,
which is the ability to recover from page faults. Let the firmware tell us
when a device supports stall.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20210526161927.24268-2-jean-philippe@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>