doc: DocBook: Fix typos in xml and template file

Fix spelling typo under Documentation/DocBook/media.
It is because these files are NOT generated by "make htmldocs",
I have to fix the files.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>