cnic: Handle RAMROD_CMD_ID_CLOSE error.

If firmware returns error status, proceed to close the iSCSI connection.
Update version to 2.5.11.

Signed-off-by: Eddie Wai <eddie.wai@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>