hw/acpi: remove unused function acpi_table_add_builtin()

Function acpi_table_add_builtin() is not used anymore.

Remove the definition and declaration.

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20190214084939.20640-3-richardw.yang@linux.intel.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>