[media] radio-si470x doc: add info about v4l2-ctl and sox+alsa
[media] radio-si470x doc: add info about v4l2-ctl and sox+alsa

Patch adds information about using v4l2-ctl utility to tune the si470x
radio and example how to use sox+alsa to redirect sound from radio sound
device to another sound device.

Signed-off-by: Alexey Klimov <cd11ba7078103ee11e48ebe9e57d87a6b52f129d@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <ad86ba2154032c9f55743a190faa2459a9d61d42@redhat.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas