[bardliao]

This is a rebase version of https://www.alsa-project.org/pipermail/alsa-devel/2018-June/137190.html

The original commit message is:

As discussed in [1], ASoC core supports multi codec DAIs
on a DAI link. However it does not do so for CPU DAIs.

So, add support for multi CPU DAIs on a DAI Link by adding
multi CPU DAI in Card instantiation, suspend and resume
functions, PCM ops, stream handling functions and DAPM.

[1]: https://www.spinics.net/lists/alsa-devel/msg71369.html

Thanks @ranj063 for the comments. I addressed some, but I need more
time or help from others for the other comments.