leaved content unchanged, only improved markup and references

* more man-like sections (add Name section)
* defined target for each stuct field description
* replace constant with ":ref:" to (field) description
Signed-off-by: NMarkus Heiser <markus.heiser@darmarIT.de>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

This is the reST migration of media's CEC part.  The migration is based
on media_tree's cec branch:

 https://git.linuxtv.org/media_tree.git

 c7169ad5 * cec media_tree/cec [media] DocBook/media: add CEC documentation
Signed-off-by: NMarkus Heiser <markus.heiser@darmarIT.de>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>