dt-bindings: qcom: Document msm8939,a7

Document samsung,a7 bindings used in its device tree.

Signed-off-by: Lin, Meng-Bo <linmengbo0689@protonmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230623100220.5284-1-linmengbo0689@protonmail.com


Signed-off-by: Bjorn Andersson <andersson@kernel.org>