MFC: (revision 1.47, 1.48)

• Add missing MCP65 id which was accidentally removed in previous commit.
• Add Analog Devices AD1984 codec id.
• Enable pcbeep control for Acer + ALC268 (nid 29). Give enough (fake) hints so the parser will grab it and allocate "speaker" control.
• Fix regression while preparing DAC and ADC for multichannel format. Since playback policy is to output to every possible path, ensure that each DAC is started.

Reported / Tested by: Guy Brand
Approved by: re (kensmith)