VIDIOC_QUERYCTRL: don't treat EINVAL as a fatal error
If a control (V4L2_CID_AUDIO_VOLUME in our case) is not supported by
VIDIOC_QUERYCTRL, EINVAL is returned. If the query operation
(VIDIOC_QUERYCTRL) is not supported at all, ENOTTY is returned. Currently
we use VIDIOC_QUERYCTRL just for the V4L2_CID_AUDIO_VOLUME and can survive
both of these errors. Let's do it.
Related to commit
e5a2c03089651659f1b4159a6d7f231b1969db0b (Work with
tuners that do not support V4L2_CID_AUDIO_VOLUME.)
Tested-by: Paulo Cavalcanti <promac@gmail.com>