trivial: fix then -> than typos in comments and documentation

- (better, more, bigger ...) then -> (...) than

Signed-off-by: Frederik Schwarzer <schwarzerf@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/kernel/pid.c b/kernel/pid.c
index 064e76a..af9224c 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -475,7 +475,7 @@
 EXPORT_SYMBOL(task_session_nr_ns);
 
 /*
- * Used by proc to find the first pid that is greater then or equal to nr.
+ * Used by proc to find the first pid that is greater than or equal to nr.
  *
  * If there is a pid at nr this function is exactly the same as find_pid_ns.
  */