bnx2x: prevent crash in shutdown flow with CNIC

There might be a crash as during shutdown flow CNIC might try
to access resources already freed by bnx2x.
Change bnx2x_close() into dev_close() in __bnx2x_remove (shutdown flow)
to guarantee CNIC is notified of the device's change of status.

Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>