dt-bindings: input: touchscreen: ilitek_ts_i2c: Absorb ili2xxx bindings

While Linux uses a different driver, the Ilitek
ILI210x/ILI2117/ILI2120/ILI251x touchscreen controller Device Tree
binding documentation is very similar.

  - Drop the fixed reg value, as some controllers use a different
    address,
  - Make reset-gpios optional, as it is not always wired.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/0c5f06c9d262c1720b40d068b6eefe58ca406601.1638539806.git.geert+renesas@glider.be

Documentation/devicetree/bindings/input/ilitek,ili2xxx.txt

-Ilitek ILI210x/ILI2117/ILI2120/ILI251x touchscreen controller
-
-Required properties:
-- compatible:
-    ilitek,ili210x for ILI210x
-    ilitek,ili2117 for ILI2117
-    ilitek,ili2120 for ILI2120
-    ilitek,ili251x for ILI251x
-
-- reg: The I2C address of the device
-
-- interrupts: The sink for the touchscreen's IRQ output
-    See ../interrupt-controller/interrupts.txt
-
-Optional properties for main touchpad device:
-
-- reset-gpios: GPIO specifier for the touchscreen's reset pin (active low)
-
-Example:
-
-	touchscreen@41 {
-		compatible = "ilitek,ili251x";
-		reg = <0x41>;
-		interrupt-parent = <&gpio4>;
-		interrupts = <7 IRQ_TYPE_EDGE_FALLING>;
-		reset-gpios = <&gpio5 21 GPIO_ACTIVE_LOW>;
-	};

Documentation/devicetree/bindings/input/touchscreen/ilitek_ts_i2c.yaml

@@ -15,6 +15,9 @@ allOf:
 properties:
   compatible:
     enum:
+      - ilitek,ili210x
+      - ilitek,ili2117
+      - ilitek,ili2120
       - ilitek,ili2130
       - ilitek,ili2131
       - ilitek,ili2132
@@ -22,11 +25,12 @@ properties:
       - ilitek,ili2322
       - ilitek,ili2323
       - ilitek,ili2326
+      - ilitek,ili251x
       - ilitek,ili2520
       - ilitek,ili2521
 
   reg:
-    const: 0x41
+    maxItems: 1
 
   interrupts:
     maxItems: 1
@@ -50,7 +54,6 @@ required:
   - compatible
   - reg
   - interrupts
-  - reset-gpios
 
 examples:
   - |