ena_com_fill_hash_function() didn't configure the rss->hash_func.

Fixes: 1738cd3e ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: NNetanel Belgazal <netanel@amazon.com>
Signed-off-by: NSameeh Jubran <sameehj@amazon.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>