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 5273d6cacc06 ("arm64: dts: meson-gx: Switch to the meson-ee-pwrc bindings")
[2] commit f4f1c8d9ace7 ("arm64: dts: meson-g12: add Everything-Else power domain controller")

Acked-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Neil Armstrong <[e-mail]>

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.