seq_buf: fix a misleading comment

The comment for seq_buf_has_overflowed() says that an overflow condition is
marked by len == size, but that's not what the code is testing.  Make the
comment match reality.

Link: https://lkml.kernel.org/r/87pm19kp0m.fsf@meer.lwn.net

Fixes: 8cd709ae ("tracing: Have seq_buf use full buffer")
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

include/linux/seq_buf.h

@@ -36,7 +36,7 @@ seq_buf_init(struct seq_buf *s, char *buf, unsigned int size)
 
 /*
  * seq_buf have a buffer that might overflow. When this happens
- * the len and size are set to be equal.
+ * len is set to be greater than size.
  */
 static inline bool
 seq_buf_has_overflowed(struct seq_buf *s)