ASoC: simple-card: Read pin switches conf from devicetree

When the routing path between a widget (e.g. "Speaker") and the codec
goes through an external amplifier, having a pin switch for this widget
allows the amplifier to be disabled when the widget is not to be used
(e.g. when using headphones).

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Mark Brown <broonie@kernel.org>