mlxsw: pci: Add mirror reason field to CQEv2

The Completion Queue Element version 2 (CQEv2) includes a field called
'mirror_reason' which indicates why the packet was mirrored to the CPU.

Add the field so that it can be used by a later patch.
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/pci_hw.h

@@ -213,6 +213,11 @@ mlxsw_pci_cqe_item_helpers(dqn, 0, 12, 12);
  */
 MLXSW_ITEM32(pci, cqe2, user_def_val_orig_pkt_len, 0x14, 0, 20);
 
+/* pci_cqe_mirror_reason
+ * Mirror reason.
+ */
+MLXSW_ITEM32(pci, cqe2, mirror_reason, 0x18, 24, 8);
+
 /* pci_cqe_owner
  * Ownership bit.
  */