ASoC: Ux500: Match platform by device node when booting Device Tree

We're getting closer to fully enabling the Ux500 ASoC driver for Device
Tree. When we switch over from using AUXDATA we'll need to match platform
by only Device Tree nodes. In this patch we NULL out the platform_name,
and supply nodes for each platform device.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>