dt-bindings: gpu: mali-bifrost: Split out MediaTek power-domains variation

In preparation for adding new bindings for new MediaTek SoCs, split out
the power-domains variation from the `else` in the current
mediatek,mt8183-mali conditional.

The sram-supply part is left in place to be disallowed for anything
that is not compatible with "mediatek,mt8183-mali" as this regulator
is MediaTek-specific and it is, and will ever be, used only for this
specific string due to the addition of the mediatek-regulator-coupler
driver.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230316102041.210269-2-angelogioacchino.delregno@collabora.com

Documentation/devicetree/bindings/gpu/arm,mali-bifrost.yaml

@@ -109,6 +109,9 @@ allOf:
           contains:
             const: amlogic,meson-g12a-mali
     then:
+      properties:
+        power-domains:
+          maxItems: 1
       required:
         - resets
   - if:
@@ -131,6 +134,8 @@ allOf:
             - const: gpu
             - const: bus
             - const: bus_ace
+        power-domains:
+          maxItems: 1
         resets:
           minItems: 3
         reset-names:
@@ -164,8 +169,6 @@ allOf:
         - power-domain-names
     else:
       properties:
-        power-domains:
-          maxItems: 1
         sram-supply: false
   - if:
       properties:
@@ -180,6 +183,8 @@ allOf:
           items:
             - const: gpu
             - const: bus
+        power-domains:
+          maxItems: 1
       required:
         - clock-names