ASoC: twl6040: Reorder HSDAC/DRV power mode change

HSDAC and HSDRV power mode change cannot be performed when the
corresponding DAC is enabled, which is now explicitly rejected.
This constraint has an important impact on eapiece path, since
it can work only in high-performance mode.

In such case, we need to force the power mode before enabling
the DACs and restore previous mode after DACs have been disabled.
That sequence cannot be achieved if the event is associated with
a switch widget, so using a supply widget instead.

Change-Id: I3bddf3dc6fc038c78f83f1eb6f21f578c80cfee2
Signed-off-by: Misael Lopez Cruz <misael.lopez@ti.com>

Conflicts:
	sound/soc/codecs/twl6040.c