ibmvnic: Do not close unopened driver during reset

Check driver state before halting it during a reset. If the driver is
not running, do nothing. Otherwise, a request to deactivate a down link
can cause an error and the reset will fail.

Signed-off-by: Thomas Falcon <tlfalcon@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>