feat: add a test command to request a Cactus SP to start wdog timer

cactus_send_twdog_cmd() API sends a direct request message to target
SP which (re)starts the Trusted Watchdog timer. The SP then sends back
a direct response message indicating successful command.

Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: If09ce76b46a6339f08f26be90e566550931fb3c7
2 files changed