[media] si4713: Added the USB driver for Si4713

This is the USB driver for the Silicon Labs development board.
It contains the Si4713 FM transmitter chip.

Signed-off-by: Dinesh Ram <dinesh.ram@cern.ch>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Tested-by: Eduardo Valentin <edubezval@gmail.com>
Acked-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
3 files changed