octeon_ep: cancel ctrl_mbox_task after intr_poll_task

intr_poll_task may queue ctrl_mbox_task. The function
octep_poll_non_ioq_interrupts_cn93_pf does this.

When removing the driver and canceling these two works, cancel
ctrl_mbox_task last to guarantee it does not run anymore.

Fixes: 24d43332

 ("octeon_ep: poll for control messages")
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Link: https://lore.kernel.org/r/20230810150114.107765-4-mschmidt@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>