firmware: ti_sci: Modify auth_boot TI-SCI API to match new version

SYSFW version 2019.01 introduces a slightly modified version of this API,
add support for it here.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Andreas Dannenberg <dannenberg@ti.com>