media: Kconfig: better support hybrid TV devices

Right now, if one has an hybrid TV card, it has to select
both analog and digital TV support, as otherwise the needed
core support won't be selected.

Change the logic to auto-select the core support for those
drivers, as this is a way more intuitive.

It should be noticed that, as now both DVB_CORE and VIDEO_DEV
defaults depends on selecting a hybrid cards, we had to remove
the explicit dependencies there, in order to avoid circular
dependencies.

That requires some tricks:

1) the prompt should not be not visible when an hybrid card
   is selected, as the user shold not change it.

2) When a media hybrid device is selected, the modular
   option for DVB_CORE and VIDEO_DEV will follow the
   MEDIA_SUPPORT dependency, as we can't have a core
   built with "y" with a driver built as module.

Note: while here, moved two pure V4L2 PCI drivers out of the
"hybrid" part of config and consider pvrusb2 as an hybrid
device.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>