acpi_tables: Add initial ACPI tables support

Add a revision 2 RSDP table only supporting an XSDT along with support
for creating generic SDT based tables.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

acpi_tables/src/lib.rs

@@ -0,0 +1,11 @@
+// Copyright © 2019 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+pub mod rsdp;
+pub mod sdt;
+
+fn generate_checksum(data: &[u8]) -> u8 {
+    (255 - data.iter().fold(0u8, |acc, x| acc.wrapping_add(*x))).wrapping_add(1)
+}