ASoC: davinci-evm: Register machine level DAPM elements with the card

Machine level DAPM widgets and routes should be registered in the card's DAPM
context, rather than in the CODEC's context.

While we are at it also drop the snd_soc_dapm_enable_pin() calls, since pins are
enabled by default and also turn the snd_soc_dapm_disable_pin() calls into
snd_soc_dapm_nc_pin() calls for unconnected pins.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>