dt-bindings: tlv320adcx140: Add GPIO config and drive config

Add properties for configuring the General Purpose Input Output (GPIO).
There are 2 settings for GPIO, configuration and the output drive type.

Signed-off-by: Camel Guo <camelg@axis.com>
Acked-by: Dan Murphy <dmurphy@ti.com>
Link: https://lore.kernel.org/r/20200918114025.18205-1-camel.guo@axis.com


Signed-off-by: Mark Brown <broonie@kernel.org>