dt-bindings: display: panel: constrain 'reg' in DSI panels (part two)

DSI-attached devices could respond to more than one virtual channel
number, thus their bindings are supposed to constrain the 'reg' property
to match hardware. Add missing 'reg' constrain for DSI-attached display
panels, based on DTS sources in Linux kernel (assume all devices take
only one channel number).

Few bindings missed previous fixup: LG SW43408 and Raydium RM69380.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Rob Herring (Arm) <[e-mail]>

Documentation/devicetree/bindings/display/panel/lg,sw43408.yaml

···
     items:
       - const: lg,sw43408
 
-  reg: true
+  reg:
+    maxItems: 1
+
   port: true
   vddi-supply: true
   vpnl-supply: true

Documentation/devicetree/bindings/display/panel/raydium,rm69380.yaml

···
       to work with the indicated panel. The raydium,rm69380 compatible shall
       always be provided as a fallback.
 
+  reg:
+    maxItems: 1
+
   avdd-supply:
     description: Analog voltage rail
 
···
   reset-gpios:
     maxItems: 1
     description: phandle of gpio for reset line - This should be active low
-
-  reg: true
 
 required:
   - compatible