arm/acpi: Prepare STAO table for Dom0

arm/acpi: Prepare STAO table for Dom0

Create STAO table for Dom0. This table is used to tell Dom0 whether it
should ignore UART defined in SPCR table or the ACPI namespace names.

Look at below url for details:
http://wiki.xenproject.org/mediawiki/images/0/02/Status-override-table.pdf

Signed-off-by: Parth Dixit <parth.dixit@linaro.org>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Julien Grall <julien.grall@arm.com>