cxgb3: Fix EEH final recovery attempt

EEH attempts to recover up 6 times.
The last attempt leaves all the ports and adapter down.hen
The driver is then unloaded, bringing the adapter down again
unconditionally. The unload will hang.
Check if the adapter is already down before trying to bring it down again.

Signed-off-by: Divy Le Ray <divy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>