sfc: do not device_attach if a reset is pending

efx_start_all can return without initialising queues as a reset is pending.
 This means that when netif_device_attach is called, the kernel can start
 sending traffic without having an initialised TX queue to send to.
This patch avoids this by not calling netif_device_attach if there is a
 pending reset.

Fixes: e283546c ("sfc:On MCDI timeout, issue an FLR (and mark MCDI to fail-fast)")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>