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/DMA-API-HOWTO.txt b/Documentation/DMA-API-HOWTO.txt
index 52618ab..2e435ad 100644
--- a/Documentation/DMA-API-HOWTO.txt
+++ b/Documentation/DMA-API-HOWTO.txt
@@ -742,7 +742,7 @@
 
 			   Closing
 
-This document, and the API itself, would not be in it's current
+This document, and the API itself, would not be in its current
 form without the feedback and suggestions from numerous individuals.
 We would like to specifically mention, in no particular order, the
 following people: