[PATCH v4 3/3] ARM64: dts: meson: meson-gx: add the SAR ADC

Martin Blumenstingl [off-list ref] writes:

Add the SAR ADC to meson-gxbb.dtsi and meson-gxl.dtsi. GXBB provides a
10-bit ADC while GXL and GXM provide a 12-bit ADC.
Some boards use resistor ladder buttons connected through one of the ADC
channels. On newer devices (GXL and GXM) some boards use pull-ups/downs
to change the resistance (and thus the ADC value) on one of the ADC
channels to indicate the board revision.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Tested-by: Neil Armstrong <redacted>
Reviewed-by: Andreas F?rber <afaerber@suse.de>

Now that IIO driver looks like it will be merged shortly, I applied this
to v4.11/dt64.

Didn't make the first pull request for arm-soc, but may still make it if
I have time to send another batch.

Kevin