ionic: fix up issues with handling EAGAIN on FW cmds

In looping on FW update tests we occasionally see the
FW_ACTIVATE_STATUS command fail while it is in its EAGAIN loop
waiting for the FW activate step to finsh inside the FW.  The
firmware is complaining that the done bit is set when a new
dev_cmd is going to be processed.

Doing a clean on the cmd registers and doorbell before exiting
the wait-for-done and cleaning the done bit before the sleep
prevents this from occurring.

Fixes: fbfb8031

 ("ionic: Add hardware init and device commands")
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>