ASoC: ssm4567: Add sense support

The ssm4567 has sensing circuitry that can be used to monitor the current
and voltage on the speaker amplifier output has well as the VBAT input.
This data can be output over the I2S interface so it can be processed by a
DSP or similar.

This patch adds the sense capture output stream to the CODEC DAI as well as
DAPM widgets that ensure that the sensing circuitry is powered up when the
capture stream is active.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>