smack: fix integer as NULL pointer warning in smack_lsm.c

security/smack/smack_lsm.c:1257:16: warning: Using plain integer as NULL pointer
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

security/smack/smack_lsm.c

@@ -1242,7 +1242,7 @@ static void smack_set_catset(char *catset, struct netlbl_lsm_secattr *sap)
 	int rc;
 	int byte;
 
-	if (catset == 0)
+	if (!catset)
 		return;
 
 	sap->flags |= NETLBL_SECATTR_MLS_CAT;