dt-bindings: display: simple-framebuffer: Document 32-bit BGR format

This is a variant of the 32-bit RGB format where the red and blue
components are swapped.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230120173103.4002342-3-thierry.reding@gmail.com

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

@@ -99,6 +99,7 @@ properties:
         * `x1r5g5b5` - 16-bit pixels, d[14:10]=r, d[9:5]=g, d[4:0]=b
         * `x2r10g10b10` - 32-bit pixels, d[29:20]=r, d[19:10]=g, d[9:0]=b
         * `x8r8g8b8` - 32-bit pixels, d[23:16]=r, d[15:8]=g, d[7:0]=b
+        * `x8b8g8r8` - 32-bit pixels, d[23:16]=b, d[15:8]=g, d[7:0]=r
     enum:
       - a1r5g5b5
       - a2r10g10b10
@@ -110,6 +111,7 @@ properties:
       - x1r5g5b5
       - x2r10g10b10
       - x8r8g8b8
+      - x8b8g8r8
 
   display:
     $ref: /schemas/types.yaml#/definitions/phandle