media: Kconfig: don't use visible for device type select

While making the menu invisible seemed a good idea, there's
a drawback: when the menu is not visible, it is not parsing
the "default" dependency.

So, instead, let's just avoid the items at the menu to be
prompted, by using the "prompt ... if" construction.

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