dt-bindings: qcom: Document msm8916-acer-a1-724

Document the new acer,a1-724 device tree bindings used in its device tree.

Signed-off-by: Lin, Meng-Bo <linmengbo0689@protonmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221123033804.148953-1-linmengbo0689@protonmail.com