net/faraday: Stop NCSI device on shutdown

This stops NCSI device when closing the network device so that the
NCSI device can be reenabled later.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>