cnic: Refactor and fix cnic_ready_to_close().

Combine RESET_RECEIVED and RESET_COMP logic and fix race condition
between these 2 events and cnic_cm_close().  In particular, we need
to (test_and_clear_bit(SK_F_OFFLD_COMPLETE, &csk->flags)) before we
update csk->state.

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