hash: remove duplicated code

hash: remove duplicated code

rte_jhash is basically like __rte_jhash_2hashes but
it returns only 1 hash, instead of 2.
In order to remove duplicated code, rte_jhash calls __rte_jhash_2hashes,
passing 0 as the second seed and returning just the first hash value.
(performance penalty is negligible)

The same is done with rte_jhash2. Also, rte_jhash2 is just an specific case
where keys are multiple of 32 bits, and where no key alignment check is required.
So,to avoid duplicated code, the function calls __rte_jhash_2hashes
with check_align = 0 (to use the optimal path)

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>