hwdb: add database entries for Focusrite Liquid Mix series

hwdb: add database entries for Focusrite Liquid Mix series

Sintefex Audio Lda. designed Liquid Mix as OEM of Focusrite Audio
Engineering, Ltd. The models serve digital signal processing service via
asynchronous transaction in IEEE 1394 bus.

The content of configuration ROM is not standard of 1394 Trading
Association.

This commit adds an rule entry for the models. At present, no driver is
developed, thus this is just for convenience to developers.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>