[media] it913x_fe: frontend and tuner driver v1.05

Fronted and Tuner Driver for ITE IT913x Series with inital support for
IT9137 integrated demodulator and tuner device.

The driver is loosely based on AF9035 series. However, support is not intended for
this device specificity.

The IT9137 tuner has been tested on UHF bands, but VHF has only been simulated.

Possible TODO the tuner sections may be separated from the main driver. All future devices
should use the it913x_fe_script_loader for other tuner devices.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
[mchehab@redhat.com: Fix an issue at the Kconfig help]
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>