ASoC: mediatek: Add suspend/resume callbacks

This adds suspend/resume callbacks, which are common for each DAI.
To be able to continue the last playback/capture after resume
when suspend was done during a playback/capture, in the callbacks
we do backup/restore of registers which were set before prepare stage.
Registers to be backup/restore are defined in a backup list array.

Signed-off-by: Koro Chen <koro.chen@mediatek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>