ACPI / scan: Add static attribute to indirect_io_hosts[]

Array indirect_io_hosts[] is declared in acpi_is_indirect_io_slave() as a
const array, which means that the array will be re-built for each call.

Optimise by adding the static attribute, which means that the array is
added to const-data pool and not re-built per function call.

Reported-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>