dpaa2-eth: prevent array underflow in update_cls_rule()

The "location" is controlled by the user via the ethtool_set_rxnfc()
function.  This update_cls_rule() function checks for array overflows
but it doesn't check if the value is negative.  I have changed the type
to unsigned to prevent array underflows.

Fixes: afb90dbb5f ("dpaa2-eth: Add ethtool support for flow classification")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/freescale/dpaa2/dpaa2-ethtool.c

@@ -635,7 +635,7 @@ static int num_rules(struct dpaa2_eth_priv *priv)
 
 static int update_cls_rule(struct net_device *net_dev,
 			   struct ethtool_rx_flow_spec *new_fs,
-			   int location)
+			   unsigned int location)
 {
 	struct dpaa2_eth_priv *priv = netdev_priv(net_dev);
 	struct dpaa2_eth_cls_rule *rule;