app/test: add new functional tests for hash functions

app/test: add new functional tests for hash functions

In order to make sure that the hash functions are returning
the correct values, new tests have been added:

- First test compares precalculated hash values with values calculated
from the existing hash functions.
- Second test compares values returned from rte_jhash2 and rte_jhash,
expecting same return (only for multiple of 4 bytes keys)

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