dt-bindings: input: imagis: Document touch keys

IST3032C (and possibly some other models) has touch keys. Document this.
Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240306-b4-imagis-keys-v3-2-2c429afa8420@skole.hrSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/touchscreen/imagis,ist3038c.yaml

@@ -9,9 +9,6 @@ title: Imagis IST30XXC family touchscreen controller
 maintainers:
   - Markuss Broks <markuss.broks@gmail.com>
 
-allOf:
-  - $ref: touchscreen.yaml#
-
 properties:
   $nodename:
     pattern: "^touchscreen@[0-9a-f]+$"
@@ -34,6 +31,10 @@ properties:
   vddio-supply:
     description: Power supply regulator for the I2C bus
 
+  linux,keycodes:
+    description: Keycodes for the touch keys
+    maxItems: 5
+
   touchscreen-size-x: true
   touchscreen-size-y: true
   touchscreen-fuzz-x: true
@@ -44,6 +45,18 @@ properties:
 
 additionalProperties: false
 
+allOf:
+  - $ref: touchscreen.yaml#
+  - if:
+      not:
+        properties:
+          compatible:
+            contains:
+              const: imagis,ist3032c
+    then:
+      properties:
+        linux,keycodes: false
+
 required:
   - compatible
   - reg