cxgb3: link fault fixes

Do not call t3_link_fault() under spinlock, as it calls msleep().
Besides, only the access to pi->link_fault needs to be serialized.

Also initialize local variables before checking the link status,
link state fields might otherwise end up containing garbage.

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