dt-bindings: arm: stm32: add compatible for stm32h747i-disco board

The board includes an STM32H747XI SoC with the following resources:
- 2 Mbytes Flash
- 1 MByte SRAM
- LCD-TFT controller
- MIPI-DSI interface
- FD-CAN
- USB 2.0 high-speed/full-speed
- Ethernet MAC
- camera interface

Detailed information can be found at:
https://www.st.com/en/evaluation-tools/stm32h747i-disco.html

Signed-off-by: Dario Binacchi <[e-mail]>
Acked-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexandre Torgue <[e-mail]>

Documentation/devicetree/bindings/arm/stm32/stm32.yaml

···
           - const: st,stm32h743
       - items:
           - enum:
+              - st,stm32h747i-disco
+          - const: st,stm32h747
+      - items:
+          - enum:
               - st,stm32h750i-art-pi
           - const: st,stm32h750
       - items: