mlxsw: reg: Add et_vlan field to SPVID register

et_vlan field is used to configure which EtherType is used when VLAN is
pushed at ingress (for untagged packets or for QinQ push mode).

It will be used to configure tagging with ether_type1 (i.e., 0x88A8) for
QinQ mode.
Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -834,6 +834,17 @@ MLXSW_ITEM32(reg, spvid, local_port, 0x00, 16, 8);
  */
 MLXSW_ITEM32(reg, spvid, sub_port, 0x00, 8, 8);
 
+/* reg_spvid_et_vlan
+ * EtherType used for when VLAN is pushed at ingress (for untagged
+ * packets or for QinQ push mode).
+ * 0: ether_type0 - (default)
+ * 1: ether_type1
+ * 2: ether_type2 - Reserved when Spectrum-1, supported by Spectrum-2
+ * Ethertype IDs are configured by SVER.
+ * Access: RW
+ */
+MLXSW_ITEM32(reg, spvid, et_vlan, 0x04, 16, 2);
+
 /* reg_spvid_pvid
  * Port default VID
  * Access: RW