net: ethernet: remove duplicated include

Remove duplicated include from mtk_ppe_offload.c.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Xu Jia <xujia39@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mediatek/mtk_ppe_offload.c

@@ -5,7 +5,6 @@
 
 #include <linux/if_ether.h>
 #include <linux/rhashtable.h>
-#include <linux/if_ether.h>
 #include <linux/ip.h>
 #include <net/flow_offload.h>
 #include <net/pkt_cls.h>