net/i40e: fix IPv4 fragment offload

net/i40e: fix IPv4 fragment offload

IPv4 fragment_offset mask was required to be 0 no matter what the
spec value was. But zero mask means not caring about fragment_offset
field then both non-frag and frag packets should hit the rule.

But the actual fragment rules should be like the following:
Only non-fragment packets can hit Rule 1:
Rule 1: mask=0x3fff, spec=0
Only fragment packets can hit rule 2:
Rule 2: mask=0x3fff, spec=0x8, last=0x2000

This patch allows the above rules.

Fixes: 42044b69c67d ("net/i40e: support input set selection for FDIR")
Cc: stable@dpdk.org
Signed-off-by: Xiaoyun Li <xiaoyun.li@intel.com>
Acked-by: Beilei Xing <beilei.xing@intel.com>