net/i40e: fix wild pointer

net/i40e: fix wild pointer

In i40e PMD code of function i40e_res_pool_free(), if valid_entry
is freed by "rte_free(valid_entry);" in the code, then the following
code for pool update may still use the wild pointer "valid_entry"
for pool info update. It seems has the risk of core dump for
using wild pointer operation, we should avoid this risk.

Fixes: 4861cde46116 ("i40e: new poll mode driver")
Cc: stable@dpdk.org
Signed-off-by: Wei Zhao <wei.zhao1@intel.com>
Reviewed-by: Jeff Guo <jia.guo@intel.com>
Reviewed-by: Xiaolong Ye <xiaolong.ye@intel.com>