cnic: Simplify route checking during iSCSI connection.

With a separate IP address for iSCSI, connections should proceed
whether or not we can get a route to the target from the network stack.
It is possible that the network IP address may not reach the iSCSI target.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: Benjamin Li <benli@broadcom.com>
Signed-off-by: Eddie Wai <waie@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>