net/iavf: fix VLAN insertion in vector path

[ upstream commit efe1b63775e8369b867f411d7bf8f61e97bd446b ]

As the VLAN insertion is partially supported in vector path,
the behavior is different in scalar and vector path.
For a VLAN packet, if using scalar path, the new VLAN tag will
be inserted after the original VLAN tag. If using vector path,
the new VLAN tag is inserted before the original VLAN tag.
To avoid any misleading, disable VLAN insertion in vector path.

Fixes: 059f18a ("net/iavf: add offload path for Tx AVX512")

Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>

doc/guides/nics/features/iavf.ini

@@ -21,7 +21,7 @@ RSS key update       = Y
 RSS reta update      = Y
 VLAN filter          = Y
 CRC offload          = Y
-VLAN offload         = Y
+VLAN offload         = P
 L3 checksum offload  = P
 L4 checksum offload  = P
 Packet type parsing  = Y

drivers/net/iavf/iavf_rxtx.h

@@ -27,13 +27,13 @@
 #define IAVF_VPMD_TX_MAX_FREE_BUF 64
 
 #define IAVF_TX_NO_VECTOR_FLAGS (				 \
+		RTE_ETH_TX_OFFLOAD_VLAN_INSERT |		 \
+		RTE_ETH_TX_OFFLOAD_QINQ_INSERT |		 \
 		RTE_ETH_TX_OFFLOAD_MULTI_SEGS |		 \
 		RTE_ETH_TX_OFFLOAD_TCP_TSO |		 \
 		RTE_ETH_TX_OFFLOAD_SECURITY)
 
 #define IAVF_TX_VECTOR_OFFLOAD (				 \
-		RTE_ETH_TX_OFFLOAD_VLAN_INSERT |		 \
-		RTE_ETH_TX_OFFLOAD_QINQ_INSERT |		 \
 		RTE_ETH_TX_OFFLOAD_IPV4_CKSUM |		 \
 		RTE_ETH_TX_OFFLOAD_SCTP_CKSUM |		 \
 		RTE_ETH_TX_OFFLOAD_UDP_CKSUM |		 \