ACPICA: Add support for 64 bit risc-v compilation

ACPICA commit 0def627be286620c64a5d4d60ce2373f119169a9

Add 64 bit risc-v architecture.  Useful for acpica tools and
incorporating ACPICA into the Firmware Test Suite.

Link: https://github.com/acpica/acpica/commit/0def627b


Signed-off-by: Colin Ian King <colin.king@canonical.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>