ASoC: hdac_hdmi: Enable pin and converter in prepare

Instead of enabling pin and cvt in pcm_open(), need to restore pin and
cvt state after system resume to restart the playback which is
paused/stopped before system suspend.
So enable pin and cvt in playback_prepare and call prepare when trigger
cmd is paused/started and resume to reconfigure pin and cvt.

Signed-off-by: Sachin Mokashi <sachinx.mokashi@intel.com>
Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>