Like the previous patches, this patch converts also to the regmap, at
this time, the cached verb writes are the target.  But this conversion
needs a bit more caution than before.

- In the old code, we just record any verbs as is, and restore them at
  resume.  For the regmap scheme, this doesn't work, since a few verbs
  like AMP or DIGI_CONVERT are asymmetrical.  Such verbs are converted
  either to the dedicated function (snd_hda_regmap_xxx_amp()) or
  changed to the unified verb.

- Some verbs have to be declared as vendor-specific ones before
  accessing via regmap.

Also, the minor optimization with codec->cached_write flag is dropped
in a few places, as this would confuse the operation.  Further
optimizations will be brought in the later patches, if any.

This conversion ends up with a drop of significant amount of codes,
mostly the helper codes that are no longer used.
Signed-off-by: Takashi Iwai <tiwai@suse.de>