Define 3 new PCMs and backends for HDMI/DP playback on GLK platform.
Here are the updated pipelines in sof-glk-da7219.m4:
PCM0 ----> volume (pipe 1) ---> SSP1 (speaker - maxim98357a, BE link 0)
PCM1 <---> volume (pipe 2,3) <--> SSP2 (headset - da7219, BE link 1)
PCM99 <---- volume (pipe 4) <--- DMIC0 (dmic capture, BE link 2)
PCM5 ----> volume (pipe 5) ---> iDisp1 (HDMI/DP playback, BE link 3)
PCM6 ----> Volume (pipe 6) ---> iDisp2 (HDMI/DP playback, BE link 4)
PCM7 ----> volume (pipe 7) ---> iDisp3 (HDMI/DP playback, BE link 5)
There is also support for changing HDMI/DP pipelines to pass-through for
validation purpose, which is commented off by default.
Pleaes note that 3 virtual widgets hifi1~3 are removed, because they'll
be created by HDMI codec driver. This m4 was verified on GLK platform.
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