net/hns3: remove unused macro

'HNS3_RXD_LKBK_B' was defined in previous versions but no used.
This patch deleted it.

Fixes: bba6366 ("net/hns3: support Rx/Tx and related operations")
Cc: stable@dpdk.org

Signed-off-by: Min Hu (Connor) <humin29@huawei.com>

drivers/net/hns3/hns3_rxtx.h

@@ -106,7 +106,6 @@
 #define HNS3_RXD_L3L4P_B			11
 
 #define HNS3_RXD_TS_VLD_B			14
-#define HNS3_RXD_LKBK_B				15
 #define HNS3_RXD_GRO_SIZE_S			16
 #define HNS3_RXD_GRO_SIZE_M			(0x3fff << HNS3_RXD_GRO_SIZE_S)