iommu/vt-d: Enumerate the scalable mode capability

The Intel vt-d spec rev3.0 introduces a new translation
mode called scalable mode, which enables PASID-granular
translations for first level, second level, nested and
pass-through modes. At the same time, the previous
Extended Context (ECS) mode is deprecated (no production
ever implements ECS).

This patch adds enumeration for Scalable Mode and removes
the deprecated ECS enumeration. It provides a boot time
option to disable scalable mode even hardware claims to
support it.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>