dt-bindings: clock: mediatek,mt7622-pciesys: Remove syscon compatible

The PCIESYS register space contains a pure clock controller, which
has no system controller register, so this definitely doesn't need
any "syscon" compatible.

As a side note, luckily no devicetree ever added the syscon string
to PCIESYS clock controller node compatibles, so this also resolves
a dtbs_check warning for mt7622.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: AngeloGioacchino Del Regno

Documentation/devicetree/bindings/clock/mediatek,mt7622-pciesys.yaml

@@ -14,11 +14,9 @@ maintainers:
 
 properties:
   compatible:
-    oneOf:
-      - items:
-          - const: mediatek,mt7622-pciesys
-          - const: syscon
-      - const: mediatek,mt7629-pciesys
+    enum:
+      - mediatek,mt7622-pciesys
+      - mediatek,mt7629-pciesys
 
   reg:
     maxItems: 1
@@ -40,7 +38,7 @@ additionalProperties: false
 examples:
   - |
     clock-controller@1a100800 {
-        compatible = "mediatek,mt7622-pciesys", "syscon";
+        compatible = "mediatek,mt7622-pciesys";
         reg = <0x1a100800 0x1000>;
         #clock-cells = <1>;
         #reset-cells = <1>;