ARM: dts: sunxi: Add R_LRADC support for A83T

Allwinner A83T SoC has a low res adc like the one in Allwinner A10 SoC.
Now the driver has been modified to support it.

Add support for it.

Signed-off-by: Ziping Chen <techping.chan@gmail.com>
Signed-off-by: Ondrej Jirman <megous@megous.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>