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

Documentation/devicetree/bindings/arm/qcom.yaml

@@ -186,6 +186,7 @@ properties:
 
       - items:
           - enum:
+              - samsung,a7
               - sony,kanuti-tulip
               - square,apq8039-t2
           - const: qcom,msm8939