net/i40e: fix flex payload rule conflict

net/i40e: fix flex payload rule conflict

With the following commands, the second flow can't
be created successfully.

1. flow create 0 ingress pattern eth / ipv4 / udp /
   raw relative is 1 pattern is 0102030405 / end
   actions drop / end
2. flow destroy 0 rule 0
3. flow create 0 ingress pattern eth / ipv4 / udp /
   raw relative is 1 pattern is 010203040506 / end
   actions drop / end

The root cause is that a flag for flex pit isn't reset.

Fixes: 6ced3dd72f5f ("net/i40e: support flexible payload parsing for FDIR")
Cc: stable@dpdk.org
Reported-by: Chenmin Sun <chenmin.sun@intel.com>
Signed-off-by: Beilei Xing <beilei.xing@intel.com>
Acked-by: Jeff Guo <jia.guo@intel.com>