dt-bindings: input: touchscreen: imagis: add missing minItems

The binding currently expects exactly 5 keycodes, which matches the
chip's theoretical maximum but probably not the number of touch keys on
any phone using the IST3032C. Add a minItems value of 2 to prevent
dt-validate complaints.

Also add another example to make sure the linux,keycodes property is
checked.

Signed-off-by: Duje Mihanović <duje@dujemihanovic.xyz>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20250824-imagis-minitems-v1-1-cea9db55e87f@dujemihanovic.xyz
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

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

@@ -35,6 +35,7 @@ properties:
 
   linux,keycodes:
     description: Keycodes for the touch keys
+    minItems: 2
     maxItems: 5
 
   touchscreen-size-x: true
@@ -87,5 +88,22 @@ examples:
         touchscreen-inverted-y;
       };
     };
+  - |
+    #include <dt-bindings/input/linux-event-codes.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      touchscreen@50 {
+        compatible = "imagis,ist3032c";
+        reg = <0x50>;
+        interrupt-parent = <&gpio>;
+        interrupts = <72 IRQ_TYPE_EDGE_FALLING>;
+        vdd-supply = <&ldo2>;
+        touchscreen-size-x = <480>;
+        touchscreen-size-y = <800>;
+        linux,keycodes = <KEY_APPSELECT>, <KEY_BACK>;
+      };
+    };
 
 ...