ftrace: Clean up __seq_open_private() return check

The return status check of __seq_open_private() is rather strange:

	iter = __seq_open_private();
	if (iter) {
		/* do stuff */
	}

	return iter ? 0 : -ENOMEM;

It makes much more sense to do the return of failure right away:

	iter = __seq_open_private();
	if (!iter)
		return -ENOMEM;

	/* do stuff */

	return 0;

This clean up will make updates to this code a bit nicer.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/ftrace.c

@@ -3355,12 +3355,13 @@ ftrace_avail_open(struct inode *inode, struct file *file)
 		return -ENODEV;
 
 	iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
-	if (iter) {
+	if (!iter)
+		return -ENOMEM;
+
 	iter->pg = ftrace_pages_start;
 	iter->ops = &global_ops;
-	}
 
-	return iter ? 0 : -ENOMEM;
+	return 0;
 }
 
 static int
@@ -3369,13 +3370,14 @@ ftrace_enabled_open(struct inode *inode, struct file *file)
 	struct ftrace_iterator *iter;
 
 	iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
-	if (iter) {
+	if (!iter)
+		return -ENOMEM;
+
 	iter->pg = ftrace_pages_start;
 	iter->flags = FTRACE_ITER_ENABLED;
 	iter->ops = &global_ops;
-	}
 
-	return iter ? 0 : -ENOMEM;
+	return 0;
 }
 
 /**