ASoC: Intel: bytcr_rt5640: fallback mechanism if MCLK is not enabled

Commit df1a2776 ("ASoC: Intel: bytcr_rt5640: add MCLK support")
was merged but the corresponding clock framework patches have not,
after being bumped from audio to clock to x86 domains. The missing
clock-related patches result in a regression starting with 4.9 with
the audio card not being created.

Rather than reverting this commit and all following updates already
queued up for 4.10, handle run-time dependency on MCLK and fall back
to the previous bit-clock mode. This provides the same functionality
as in 4.8 for Baytrail devices. On Baytrail-CR most devices remain
silent with this fallback but additional patches are needed anyway.
As suggested by Mark Brown, the fallback is only allowed with -ENOENT,
all other run-time errors, including -EPROBE_DEFER, will stop the probe
with no sound card registered.

This patch should be applied to -stable as well as ASoC 4.10 fixes

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