Treat "ihfforcall" audio sink as an alias for "ihf"

Some devices use just "ihf", some use separate "ihfforcall" during
active call. Since MCE uses this information only as input for
blanking policy during active call, the two can be treated equally.

Also emit warning to journal if unknown audio sinks are seen to
make future changes in audio policy changes easier to detect / debug.

[mce] Treat "ihfforcall" audio sink as an alias for "ihf"
Merge pull request #123 from spiiroin/ihfforcall_audio_sink

Treat "ihfforcall" audio sink as an alias for "ihf"