net: sched: fix coding style issues

This patch fix checkpatch issues for upcomming patches according to the
sched api file. It changes mostly how to check on null pointer.

Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_gred.c

@@ -306,12 +306,13 @@ static inline int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps)
 	struct tc_gred_sopt *sopt;
 	int i;
 
-	if (dps == NULL)
+	if (!dps)
 		return -EINVAL;
 
 	sopt = nla_data(dps);
 
-	if (sopt->DPs > MAX_DPs || sopt->DPs == 0 || sopt->def_DP >= sopt->DPs)
+	if (sopt->DPs > MAX_DPs || sopt->DPs == 0 ||
+	    sopt->def_DP >= sopt->DPs)
 		return -EINVAL;
 
 	sch_tree_lock(sch);
@@ -470,7 +471,7 @@ static int gred_init(struct Qdisc *sch, struct nlattr *opt)
 	struct nlattr *tb[TCA_GRED_MAX + 1];
 	int err;
 
-	if (opt == NULL)
+	if (!opt)
 		return -EINVAL;
 
 	err = nla_parse_nested(tb, TCA_GRED_MAX, opt, gred_policy, NULL);