ACPICA: Add SVKL table headers

ACPICA commit b5e6bcf69dbb9877481992d5ce86008cfb94f5b8

SVKL (Storage Volume Key Location Table) is used by BIOS/Firmware
to share storage volume encryption key's with OS. It will be used
by userspace to decrypt and mount encrypted drives.

So add SVKL table signature and add it to known signatures array
support SVKL.

You can find details about the SVKL table in TDX specfication
titled "Guest-Host-Communication Interface (GHCI) for Intel
Trust Domain Extensions (Intel® TDX)", sec 4.4 and in ACPI
specification r6.4, sec 5.2.6.

Link: https://software.intel.com/content/dam/develop/external/us/en/documents/intel-tdx-guest-hypervisor-communication-interface.pdf
Link: https://github.com/acpica/acpica/commit/b5e6bcf6


Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Erik Kaneda <erik.kaneda@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>