ASoC: Intel: Atom: flip logic for gain Switch

The upstreamed code modified the control names from Mute to
Switch without changing the logic. To get audio working the Switch
needs to be off which isn't aligned with normal ALSA conventions.

Inverting the logic now so that Switch Off means mute and Switch On
means active audio using the specific volume setting.

Signed-off-by: Sebastien Guiriec <sebastien.guiriec@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>