[media] ttusb2: Kconfig patch to auto-select frontends for TechnoTrend CT-3650

The ttusb2 module is already updated to recognize the TechnoTrend CT-3650
CI DVB C/T USB2.0 receiver in addition to the Pinnacle 400e. But if
MEDIA_SUBDRV_AUTOSELECT is used, the required tuner and demodulator
modules are not automatically selected. Here's a patch to fix that and add a
note of the CT-3650 to the online help of the ttusb2 module.
This patch applies cleanly to 3.7.6 and other 3.7.x kernels.

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