regulator: dt-bindings: rpi-panel: Add regulator for 7" Raspberry Pi 720x1280

Document regulator compatible string for the 7" Raspberry Pi 720x1280 DSI
panel based on ili9881. This is the Raspberry Pi DSI Panel V2. The newer
Raspberry Pi 5" and 7" panels have a slightly different register map to
the original one and offers PWM backlight control.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Link: https://patch.msgid.link/20250609000748.1665219-1-marek.vasut+renesas@mailbox.org
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Marek Vasut

Documentation/devicetree/bindings/regulator/raspberrypi,7inch-touchscreen-panel-regulator.yaml

@@ -12,14 +12,17 @@ maintainers:
 description: |
   The RaspberryPi 7" display has an ATTINY88-based regulator/backlight
   controller on the PCB, which is used to turn the display unit on/off
-  and control the backlight.
+  and control the backlight. The V2 supports 5" and 7" panels and also
+  offers PWM backlight control.
 
 allOf:
   - $ref: regulator.yaml#
 
 properties:
   compatible:
-    const: raspberrypi,7inch-touchscreen-panel-regulator
+    enum:
+      - raspberrypi,7inch-touchscreen-panel-regulator
+      - raspberrypi,touchscreen-panel-regulator-v2
 
   reg:
     maxItems: 1