[media] DocBook: Better document enum fe_modulation

Instead of using programlisting, use a table, as this provides
a better view of the structure.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --cc Documentation/DocBook/media/dvb/dvbproperty.xml
Simple merge

diff --cc Documentation/DocBook/media/dvb/frontend.xml
Simple merge

diff --cc include/uapi/linux/dvb/frontend.h
Simple merge