igbvf: work around i350 erratum

On i350 VF devices, VLAN tags will be byte-swapped in the receive
descriptor only when received packets are looped back from other
VFs. Check for this condition and swab the tag if needed.

Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igbvf/igbvf.h

@@ -295,7 +295,7 @@ struct igbvf_info {
 
 /* hardware capability, feature, and workaround flags */
 #define IGBVF_FLAG_RX_CSUM_DISABLED             (1 << 0)
-
+#define IGBVF_FLAG_RX_LB_VLAN_BSWAP		(1 << 1)
 #define IGBVF_RX_DESC_ADV(R, i)     \
 	(&((((R).desc))[i].rx_desc))
 #define IGBVF_TX_DESC_ADV(R, i)     \