octeon_ep: implement device unload control net API

Device unload control net function should inform firmware
of driver unload to let it take necessary actions to cleanup.

Signed-off-by: Shinas Rasheed <srasheed@marvell.com>
Link: https://lore.kernel.org/r/20231129045348.2538843-2-srasheed@marvell.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>