dt-bindings: arm: qcom: document Mikrotik RB3011 board

Add compatible for existing Mikrotik RB3011 board.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221017014653.12970-1-krzysztof.kozlowski@linaro.org