ASoC: Intel: bytcr_rt5640: add MCLK support

Use platform clocks "pmc_plt_clk_3" when MCLK quirk is defined.
By default always enable the 19.2 MHz PLL.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>