ARM: dts: suniv: f1c100s: add LRADC node

ARM: dts: suniv: f1c100s: add LRADC node

The Allwinner F1C100s series of SoCs contain a LRADC (aka. KEYADC)
compatible to the version in other SoCs.
The manual doesn't mention the ratio of the input voltage that is used,
but comparing actual measurements with the values in the register
suggests that it is 3/4 of Vref.

Add the DT node describing the base address and interrupt. As in the
older SoCs, there is no explicit reset or clock gate, also there is a
dedicated, non-multiplexed pin, so need for more properties.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20221107005433.11079-8-andre.przywara@arm.com
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>