dt-bindings: mailbox: qcom: correct the list of platforms using clocks

The schema incorrectly lists some of the platforms in the statement
requiring clocks/clock-names. Correct this by moving platforms not
requiring additional clocks to the separate clause.

Fixes: 0d17014e ("dt-bindings: mailbox: Add binding for SDX55 APCS")
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>