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/scsi/osst.txt b/Documentation/scsi/osst.txt
index f536907..2b21890 100644
--- a/Documentation/scsi/osst.txt
+++ b/Documentation/scsi/osst.txt
@@ -40,7 +40,7 @@
 
 History
 -------
-In the first place, osst shared it's identity very much with st. That meant
+In the first place, osst shared its identity very much with st. That meant
 that it used the same kernel structures and the same device node as st.
 So you could only have either of them being present in the kernel. This has
 been fixed by registering an own device, now.