net: microchip: sparx5: Update return value check for vcap_get_rule()

As Simon Horman suggests, update vcap_get_rule() to always
return an ERR_PTR() and update the error detection conditions to
use IS_ERR(), so use IS_ERR() to check the return value.
Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Suggested-by: Simon Horman <horms@kernel.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/microchip/sparx5/sparx5_tc_flower.c

@@ -1274,7 +1274,7 @@ static int sparx5_tc_free_rule_resources(struct net_device *ndev,
 	int ret = 0;
 
 	vrule = vcap_get_rule(vctrl, rule_id);
-	if (!vrule || IS_ERR(vrule))
+	if (IS_ERR(vrule))
 		return -EINVAL;
 
 	sparx5_tc_free_psfp_resources(sparx5, vrule);