amd-xgbe: fix ->rss_hash_type

There was a missing break statement so we set everything to
PKT_HASH_TYPE_L3 even when we intended to use PKT_HASH_TYPE_L4.

Fixes: 5b9dfe29 ('amd-xgbe: Provide support for receive side scaling')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>