conf/ucm: bytcr-rt5651: Add support for a headset-mic on IN2

The first design with the headset-mic on IN2 rather then the
default / reference-design IN3 has shown up.

Add a new ucm/codecs/rt5651/IN2-HeadsetMic.conf snippet to deal with this
and include this in the default non board-specific bytcr-rt5651.conf.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>