ALSA: usb - Don't create "Speaker" mixer controls on headphones and headsets

A lot of headsets/headphones have a "Speaker" mixer control. This confuses
PulseAudio to think it is a speaker instead of a headphone/headset.
Therfore, we rename it to "Headphone".

We determine if something is a headphone similar to how udev determines
form factor (see 78-sound-card.rules).

BugLink: https://bugs.launchpad.net/bugs/1082357


Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>