eth: fbnic: use fw uptime to detect fw crashes

eth: fbnic: use fw uptime to detect fw crashes

Currently we only detect FW crashes when it stops responding
to heartbeat messages. FW has a watchdog which will reset it
in case of crashes. Use FW uptime sent in the ownership and
heartbeat messages to detect that the watchdog has fired
(uptime went down).

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20250916231420.1693955-3-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>