Properly handle tristate dependencies on USB/PCI menus

As USB/PCI/MEDIA_SUPPORT dependencies can be tristate, we can't
simply make the bool menu to be dependent on it. Everything below
the menu should also depend on it, otherwise, we risk to allow
building them with 'y', while only 'm' would be supported.

So, add an IF just before everything below, in order to avoid
such risks.

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