dt-bindings: display: Add powertip,{st7272|hx8238a} as DT Schema description

This patch provides the DT Schema description of:
- powertip,st7272  320 x 240 LCD display
- powertip,hx8238a 320 x 240 LCD display

Used with the different HW revisions of btt3 devices.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20250109154149.1212631-1-lukma@denx.de
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

Documentation/devicetree/bindings/display/panel/powertip,hx8238a.yaml

@@ -0,0 +1,29 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/panel/powertip,hx8238a.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Powertip Electronic Technology Co. 320 x 240 LCD panel
+
+maintainers:
+  - Lukasz Majewski <lukma@denx.de>
+
+allOf:
+  - $ref: panel-dpi.yaml#
+
+properties:
+  compatible:
+    items:
+      - const: powertip,hx8238a
+      - {} # panel-dpi, but not listed here to avoid false select
+
+  height-mm: true
+  panel-timing: true
+  port: true
+  power-supply: true
+  width-mm: true
+
+additionalProperties: false
+
+...

Documentation/devicetree/bindings/display/panel/powertip,st7272.yaml

@@ -0,0 +1,29 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/panel/powertip,st7272.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Powertip Electronic Technology Co. 320 x 240 LCD panel
+
+maintainers:
+  - Lukasz Majewski <lukma@denx.de>
+
+allOf:
+  - $ref: panel-dpi.yaml#
+
+properties:
+  compatible:
+    items:
+      - const: powertip,st7272
+      - {} # panel-dpi, but not listed here to avoid false select
+
+  height-mm: true
+  panel-timing: true
+  port: true
+  power-supply: true
+  width-mm: true
+
+additionalProperties: false
+
+...