ACPI: tables: Add support for NBFT

Add support for the NVMe Boot Firmware Table (NBFT) to facilitate
booting from NVM Express namespaces which are accessed via
NVMe over Fabrics (NVMe-oF).

Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Reviewed-by: John Meneghini <jmeneghi@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>