ASoC: simple-card: simplify code

In the non-DT sequence, the platform data is copied as a whole to the
dynamic card info and the same pointer 'cinfo' is used to copy the
platform information to the card.

Use 'priv' as the pointer to the dynamic card info and copy only the
useful information from the platform data.

Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mark Brown <broonie@linaro.org>