Documentation/: it's -> its where appropriate

Fix obvious cases of "it's" being used when "its" was meant.

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/Documentation/dvb/contributors.txt b/Documentation/dvb/contributors.txt
index 4865add..47c3009 100644
--- a/Documentation/dvb/contributors.txt
+++ b/Documentation/dvb/contributors.txt
@@ -1,7 +1,7 @@
 Thanks go to the following people for patches and contributions:
 
 Michael Hunold <m.hunold@gmx.de>
-  for the initial saa7146 driver and it's recent overhaul
+  for the initial saa7146 driver and its recent overhaul
 
 Christian Theiss
   for his work on the initial Linux DVB driver