ASoC: Intel: byt-rt5640: Switch ADSP and RT5640 I2S roles

This experimental patch changes the DSP and RT5640 I2S roles. It changes
codec from I2S slave to master and uses I2S slave firmware for ADSP.

As codec is now I2S master it cannot take BCLK as its PLL input clock.
Take PLL input from MCLK pin and feed it from SoC's clock output.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>