ASoC: simple-card: Add device's module clock selection.

ASoC: simple-card: Add device's module clock selection.

Try to get the device's module clock if the dt has no clocks and
system-clock-frequency properties.

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>