pps: timestamp is always passed to dcd_change()

Remove the code that gatheres timestamp in pps_tty_dcd_change() in case
passed ts parameter is NULL because it never happens in the current code.
Fix comments as well.

Signed-off-by: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Acked-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/serial/tty.txt b/Documentation/serial/tty.txt
index 7c90050..540db41 100644
--- a/Documentation/serial/tty.txt
+++ b/Documentation/serial/tty.txt
@@ -107,7 +107,7 @@
 
 dcd_change()	-	Report to the tty line the current DCD pin status
 			changes and the relative timestamp. The timestamp
-			can be NULL.
+			cannot be NULL.
 
 
 Driver Access