dt-bindings: power: amlogic,meson-gx-pwrc: mark bindings as deprecated

The amlogic,meson-gx-pwrc-vpu compatible isn't used anymore since [1]
was merged in v5.8-rc1 and amlogic,meson-g12a-pwrc-vpu either since [2]
was merged in v5.3-rc1.

[1] commit 5273d6ca ("arm64: dts: meson-gx: Switch to the meson-ee-pwrc bindings")
[2] commit f4f1c8d9 ("arm64: dts: meson-g12: add Everything-Else power domain controller")
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221117-b4-amlogic-bindings-convert-v2-6-36ad050bb625@linaro.orgSigned-off-by: Neil Armstrong <neil.armstrong@linaro.org>

Documentation/devicetree/bindings/power/amlogic,meson-gx-pwrc.txt

-Amlogic Meson Power Controller
-==============================
+Amlogic Meson Power Controller (deprecated)
+===========================================
 
 The Amlogic Meson SoCs embeds an internal Power domain controller.