net/sched: flower: Avoid overwriting error messages

The various error paths of tc_setup_offload_action() now report specific
error messages. Remove the generic messages to avoid overwriting the
more specific ones.

Before:

 # tc filter add dev dummy0 ingress pref 1 proto ip flower skip_sw dst_ip 198.51.100.1 action police rate 100Mbit burst 10000
 Error: cls_flower: Failed to setup flow action.
 We have an error talking to the kernel

After:

 # tc filter add dev dummy0 ingress pref 1 proto ip flower skip_sw dst_ip 198.51.100.1 action police rate 100Mbit burst 10000
 Error: act_police: Offload not supported when conform/exceed action is "reclassify".
 We have an error talking to the kernel

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_flower.c

@@ -468,8 +468,6 @@ static int fl_hw_replace_filter(struct tcf_proto *tp,
 				      cls_flower.common.extack);
 	if (err) {
 		kfree(cls_flower.rule);
-		NL_SET_ERR_MSG_MOD(cls_flower.common.extack,
-				   "Failed to setup flow action");
 
 		return skip_sw ? err : 0;
 	}
@@ -2358,8 +2356,6 @@ static int fl_reoffload(struct tcf_proto *tp, bool add, flow_setup_cb_t *cb,
 					      cls_flower.common.extack);
 		if (err) {
 			kfree(cls_flower.rule);
-			NL_SET_ERR_MSG_MOD(cls_flower.common.extack,
-					   "Failed to setup flow action");
 			if (tc_skip_sw(f->flags)) {
 				__fl_put(f);
 				return err;