Although the recommended usage is the DVBv5 API calls, the
documentation doesn't make it clear about what's the recommended
calls and what's legacy.

So, move the legacy API bits to a separate xml, putting them into
a new section.

Please notice that more changes are needed, since some of the
bits there are cross-referenced elsewhere.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>