s390/qeth: remove RECOVER state

The offline code uses a specific RECOVER state to indicate that the
interface should be brought up when a qeth device is set online again.

Rather than having a specific card-state for this, just put it in an
internal flag bit and set the state to DOWN. When working with the
card's state transitions, this reduces the complexity quite a bit.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>