ethdev: add the hash key size per device

ethdev: add the hash key size per device

To support querying hash key size per port, an new field of
'hash_key_size' was added in 'struct rte_eth_dev_info' for storing
hash key size in bytes.

The correct hash key size in bytes should be filled into the
'struct rte_eth_dev_info', to support querying it.

Signed-off-by: Helin Zhang <helin.zhang@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>