dt-bindings: arm: rockchip: Correct vendor for Banana Pi R2 Pro

The vendor for this board was incorrectly listed as Rockchip. Fix this
now while they are not used anywhere, in the future they may be used by
bootloader to select dts.

Update the vendor to Sinovoip.
Signed-off-by: Tim Lunn <tim@feathertop.org>
Fixes: 8ad88512 ("dt-bindings: rockchip: Add BananaPi R2 Pro Board")
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240214040731.3069111-3-tim@feathertop.orgSigned-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -943,9 +943,9 @@ properties:
           - const: rockchip,rk3568-evb1-v10
           - const: rockchip,rk3568
 
-      - description: Rockchip RK3568 Banana Pi R2 Pro
+      - description: Sinovoip RK3568 Banana Pi R2 Pro
         items:
-          - const: rockchip,rk3568-bpi-r2pro
+          - const: sinovoip,rk3568-bpi-r2pro
           - const: rockchip,rk3568
 
       - description: Sonoff iHost Smart Home Hub