snd_hda: Enable microphone redirection for ALC257

[christos]

Summary

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

[christos]

@wulf Is this change breaking something on your device?

[mav]

As with any other patches of the kind you may either fix the "issue" or break sound completely by producing invalid configuration. Unless the configuration is already broken and require fixing, it should better be handled with /dev/dsp redirection, as we discussed before.

[christos]

Abandoning not exactly because of mav@'s comment per-se, but because I didn't realize that this patch could be problematic for people who plug into the headphone jack, but with headphones that do not have a microphone as well. I guess this is better set in /boot/device.hints.