V4L/DVB (3326): Fix stereo and standard reporting of msp3400 (esp. for radio)

- Add VIDIOC_LOG_STATUS to the radio device ioctl list.
- Reduce the confusion between modes and standards
- Fix stereo reporting for radio.
- Don't set i2c configuration if the chip doesn't support it.
- Fix reporting of current standard for radio.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@brturbo.com.br>