net: cxgb3: reject unsupported coalescing params

Set ethtool_ops->supported_coalesce_params to let
the core reject unsupported coalescing parameters.

This driver did not previously reject unsupported parameters.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb3/cxgb3_main.c

@@ -2104,6 +2104,7 @@ static void get_wol(struct net_device *dev, struct ethtool_wolinfo *wol)
 }
 
 static const struct ethtool_ops cxgb_ethtool_ops = {
+	.supported_coalesce_params = ETHTOOL_COALESCE_RX_USECS,
 	.get_drvinfo = get_drvinfo,
 	.get_msglevel = get_msglevel,
 	.set_msglevel = set_msglevel,