mlxsw: spectrum: Fix memory leak in mlxsw_sp_flower_stats()

The function mlxsw_sp_flower_stats() calls mlxsw_sp_acl_ruleset_get() to
obtain a ruleset reference. If the subsequent call to
mlxsw_sp_acl_rule_lookup() fails to find a rule, the function returns
an error without releasing the ruleset reference, causing a memory leak.

Fix this by using a goto to the existing error handling label, which
calls mlxsw_sp_acl_ruleset_put() to properly release the reference.

Fixes: 7c1b8eb ("mlxsw: spectrum: Add support for TC flower offload statistics")
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20251112052114.1591695-1-zilin@seu.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: GoodLuck612

drivers/net/ethernet/mellanox/mlxsw/spectrum_flower.c

@@ -830,8 +830,10 @@ int mlxsw_sp_flower_stats(struct mlxsw_sp *mlxsw_sp,
 		return -EINVAL;
 
 	rule = mlxsw_sp_acl_rule_lookup(mlxsw_sp, ruleset, f->cookie);
-	if (!rule)
-		return -EINVAL;
+	if (!rule) {
+		err = -EINVAL;
+		goto err_rule_get_stats;
+	}
 
 	err = mlxsw_sp_acl_rule_get_stats(mlxsw_sp, rule, &packets, &bytes,
 					  &drops, &lastuse, &used_hw_stats);