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.org


Signed-off-by: Heiko Stuebner <heiko@sntech.de>