ASoC: davinci-evm: Add device tree binding

ASoC: davinci-evm: Add device tree binding

Device tree support for Davinci Machine driver

When the board boots with device tree, the driver will receive card,
codec, dai interface details (like the card name, DAPM routing map,
phandle for the audio components described in the dts file, codec mclk
speed). The card will be set up based on this information. Since the
routing is provided via DT we can mark the card fully routed so core
can take care of disconnecting the unused pins.

Signed-off-by: Hebbar, Gururaja <gururaja.hebbar@ti.com>
Signed-off-by: Darren Etheridge <detheridge@ti.com>
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>