kernel-doc: use no-doc option

When asked by a template to include all functions from a file,
it will also include DOC: sections wreaking havoc in the generated
docbook file. This patch makes it use the new -no-doc-sections
flag for kernel-doc to avoid this.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>