intel_iommu: Introduce a property to control FS1GP cap bit setting

intel_iommu: Introduce a property to control FS1GP cap bit setting

This gives user flexibility to turn off FS1GP for debug purpose.

It is also useful for future nesting feature. When host IOMMU doesn't
support FS1GP but vIOMMU does, nested page table on host side works
after turning FS1GP off in vIOMMU.

This property has no effect when vIOMMU is in legacy mode or x-flts=off
in scalable modme.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Clément Mathieu--Drif<clement.mathieu--drif@eviden.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20241212083757.605022-20-zhenzhong.duan@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>