V4L/DVB (5539): Radio-rtrack2.c Added VIDIOC_[GS]_AUDIO and VIDIOC_[S|G]_INPUT

Implements VIDIOC_[GS]_AUDIO and VIDIOC_[S|G]_INPUT on radio-rtrack2

Signed-off-by: Douglas Schilling Landgraf <dougsland@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>