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>
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 74c22b4..96a5e5d 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -669,7 +669,7 @@ int qdisc_class_hash_init(struct Qdisc_class_hash *clhash)
 	unsigned int size = 4;
 
 	clhash->hash = qdisc_class_hash_alloc(size);
-	if (clhash->hash == NULL)
+	if (!clhash->hash)
 		return -ENOMEM;
 	clhash->hashsize  = size;
 	clhash->hashmask  = size - 1;