ASoC: pxa: Pass correct DAPM context to {corgi,poodle,spitz}_ext_control

When calling {corgi,poodle,spitz}_ext_control() from the startup callback we
pass the CODEC's DAPM context instead of the card's DAPM context. This is not a
problem per se since all the DAPM functions in ext_control() fallback to widgets
from other DAPM contexts, but passing the card's context is more consistent.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>