net/iavf: add TSO offload use basic path

IAVF choices VECTOR TX path or Basic TX path by macro
IAVF_NO_VECTOR_FLAGS. TSO offload only processed by Basic TX path.

Fixes: 605c6f9 ("net/avf: convert to new Rx and Tx offload API")
Cc: stable@dpdk.org

Signed-off-by: Tao Zhu <taox.zhu@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>

drivers/net/iavf/iavf_rxtx.h

@@ -28,6 +28,7 @@
 		DEV_TX_OFFLOAD_VLAN_INSERT |		 \
 		DEV_TX_OFFLOAD_SCTP_CKSUM |		 \
 		DEV_TX_OFFLOAD_UDP_CKSUM |		 \
+		DEV_TX_OFFLOAD_TCP_TSO |		 \
 		DEV_TX_OFFLOAD_TCP_CKSUM)
 
 #define DEFAULT_TX_RS_THRESH     32