i40vf: don't stop me now

If a reset occurs when the netdev is closed, the reset task will hang in
napi_disable, causing deadlocks and general grumpiness.

Check to make sure the device is actually running before stopping
everything. This allows the reset task to complete and have a real good
time.

Change-ID: Iaaea84acbcb9b3810c216b14c3326e4287b75b58
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>