net: ena: remove set but not used variable 'hash_key'

drivers/net/ethernet/amazon/ena/ena_com.c: In function ena_com_hash_key_allocate:
drivers/net/ethernet/amazon/ena/ena_com.c:1070:50:
 warning: variable hash_key set but not used [-Wunused-but-set-variable]

commit 6a4f7dc8 ("net: ena: rss: do not allocate key when not supported")
introduced this, but not used, so remove it.
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/amazon/ena/ena_com.c

@@ -1067,18 +1067,14 @@ static void ena_com_hash_key_fill_default_key(struct ena_com_dev *ena_dev)
 static int ena_com_hash_key_allocate(struct ena_com_dev *ena_dev)
 {
 	struct ena_rss *rss = &ena_dev->rss;
-	struct ena_admin_feature_rss_flow_hash_control *hash_key;
 	struct ena_admin_get_feat_resp get_resp;
 	int rc;
 
-	hash_key = (ena_dev->rss).hash_key;
-
 	rc = ena_com_get_feature_ex(ena_dev, &get_resp,
 				    ENA_ADMIN_RSS_HASH_FUNCTION,
 				    ena_dev->rss.hash_key_dma_addr,
 				    sizeof(ena_dev->rss.hash_key), 0);
 	if (unlikely(rc)) {
-		hash_key = NULL;
 		return -EOPNOTSUPP;
 	}