bnx2x: Ack unknown VF messages

A PF should ack the firmware when receiving unknown messages through the VF's
mailbox. This prevents the VF mailbox from being stuck in case of a VF sending
a message unknown to the PF (e.g. VF with more advanced version).
Signed-off-by: NAriel Elior <ariele@broadcom.com>
Signed-off-by: NYuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: NEilon Greenstein <eilong@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_vfpf.c

@@ -1605,8 +1605,11 @@ static void bnx2x_vf_mbx_request(struct bnx2x *bp, struct bnx2x_virtf *vf,
 			bnx2x_vf_mbx_resp(bp, vf);
 		} else {
 			/* can't send a response since this VF is unknown to us
-			 * just unlock the channel and be done with.
+			 * just ack the FW to release the mailbox and unlock
+			 * the channel.
 			 */
+			storm_memset_vf_mbx_ack(bp, vf->abs_vfid);
+			mmiowb();
 			bnx2x_unlock_vf_pf_channel(bp, vf,
 						   mbx->first_tlv.tl.type);
 		}