dt-bindings: display: panel-simple: Add On Tat Industrial Company KD50G21-40NT-A1

Document On Tat Industrial Company KD50G21-40NT-A1 5" WVGA TFT LCD panel.

The LCD module specification can be found at:
https://cdn-shop.adafruit.com/datasheets/KD50G21-40NT-A1.pdf

Signed-off-by: Liu Ying <[e-mail]>
Acked-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Neil Armstrong <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

Documentation/devicetree/bindings/display/panel/panel-simple.yaml

···
       - okaya,rs800480t-7x0gp
         # Olimex 4.3" TFT LCD panel
       - olimex,lcd-olinuxino-43-ts
+        # On Tat Industrial Company 5" DPI TFT panel.
+      - ontat,kd50g21-40nt-a1
         # On Tat Industrial Company 7" DPI TFT panel.
       - ontat,yx700wv03
         # OrtusTech COM37H3M05DTC Blanview 3.7" VGA portrait TFT-LCD panel