acpi: fix struct acpi_xsdt

The size of the ACPI table header is not a multiple of 8. We have to mark
struct acpi_xsdt as packed to correctly access field Entry.

Add a unit test for the offsets of field Entry in the RSDT and XSDT tables.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2 files changed