ASoC: da7219: Support HP detect procedure when MCLK not present

Currently the driver code assumes that MCLK will be present during
the procedure, or if it has control of MCLK then it can make sure
it's enabled. Some platforms however do not provide MCLK to the
driver in this way, and will not leave MCLK enabled when Codec is
in STANDBY state.

This patch adds support for the HP detect procedure when running
from the device's internal oscillator, to ensure all platforms
can make use of this feature correctly.

Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Signed-off-by: Mark Brown <broonie@kernel.org>