Add code to allow the ASI Tx output to be placed into High-z mode
during unused ASI cycles.  This allows for other devices that may be on
the bus to drive the ASI out. By default the 320adcx140 sends 0's for
unused cycles.
Signed-off-by: Dan Murphy <dmurphy@ti.com>
Link: https://lore.kernel.org/r/20200915190606.1744-4-dmurphy@ti.comSigned-off-by: Mark Brown <broonie@kernel.org>