This patch fixes the static check warning due to missing handling leg of
unsupported L3 protocol type in the hns3_get_l4_protocol() function.

Fixes: 76ad4f0e ("net: hns3: Add support of HNS3 Ethernet Driver for
hip08 SoC")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>