dt-bindings: ata: qcom,apq8064-ahci: add to dtschema

The APQ8064 SATA AHCI controller is used in apq8064.dtsi, although it
was not documented in the old text bindings.
Add its compatible to ahci-platform.yaml.

Signed-off-by: Rayyan Ansari <rayyan.ansari@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>