V4L/DVB (3299): Kconfig: DVB_USB_CXUSB depends on DVB_LGDT330X and DVB_MT352

- rename DVB_USB_CXUSB one-liner description to:
  Conexant USB2.0 hybrid reference design support.
- with the addition of bluebird support to dvb-usb-cxusb,
  it now depends on lgdt330x and mt352 modules.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>