dt-bindings: input: sun4i-lradc-keys: Add A64 compatible

Add the A64 compatible with a fallback to the A83T compatible.
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

Documentation/devicetree/bindings/input/sun4i-lradc-keys.txt

@@ -5,6 +5,7 @@ Required properties:
  - compatible: should be one of the following string:
 		"allwinner,sun4i-a10-lradc-keys"
 		"allwinner,sun8i-a83t-r-lradc"
+		"allwinner,sun50i-a64-lradc", "allwinner,sun8i-a83t-r-lradc"
  - reg: mmio address range of the chip
  - interrupts: interrupt to which the chip is connected
  - vref-supply: powersupply for the lradc reference voltage