hash: fix out-of-bound write while freeing key slot

hash: fix out-of-bound write while freeing key slot

Add a debug check for out-of-bound write while freeing the key slot.

Coverity issue: 325733
Fixes: e605a1d36ca7 ("hash: add lock-free r/w concurrency")
Cc: stable@dpdk.org
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>