hash: fix check of parameter
hash: fix check of parameter

Coverity flags that 'h' variable is used before
it's checked for NULL. This patch fixes this issue.

Coverity issue: 363625
Fixes: 769b2de7fb52 ("hash: implement RCU resources reclamation")

Signed-off-by: Yunjian Wang <9985a735d5d5f80ef648228b285228d6eb6eaf45@huawei.com>
Reviewed-by: Dharmik Thakkar <724f3610823e4b14afc73144686337ac966281c2@arm.com>
Acked-by: Yipeng Wang <7cbe00ff6364999b5548d30abb0722f7c2a7092c@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk