USB-Audio: Blacklist iec958 for some USB devices

USB-Audio: Blacklist iec958 for some USB devices

Some common USB devices are analog only, so prevent the digital
devices from being opened. This simplifies probing the device
in PulseAudio.

I have a "Logitech USB Headset" myself, the "Logitech Web Camera"
was reported by Raymond Yau, and the "Blue Snowball" was reported by
Andy Whitcroft.

Cc: Andy Whitcroft <andy.whitcroft@canonical.com>
Cc: Raymond Yau <superquad.vortex2@gmail.com>
BugLink: https://bugs.launchpad.net/bugs/940145
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>