dt-binding: gce: add gce header file for mt8192

Add documentation for the mt8192 gce.

Add gce header file defined the gce hardware event,
subsys number and constant for mt8192.
Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

Documentation/devicetree/bindings/mailbox/mtk-gce.txt

@@ -9,8 +9,8 @@ CMDQ driver uses mailbox framework for communication. Please refer to
 mailbox.txt for generic information about mailbox device-tree bindings.
 
 Required properties:
-- compatible: can be "mediatek,mt8173-gce", "mediatek,mt8183-gce" or
-  "mediatek,mt6779-gce".
+- compatible: can be "mediatek,mt8173-gce", "mediatek,mt8183-gce",
+  "mediatek,mt8192-gce" or "mediatek,mt6779-gce".
 - reg: Address range of the GCE unit
 - interrupts: The interrupt signal from the GCE block
 - clock: Clocks according to the common clock binding
@@ -36,7 +36,8 @@ Optional properties for a client device:
   size: the total size of register address that GCE can access.
 
 Some vaules of properties are defined in 'dt-bindings/gce/mt8173-gce.h',
-'dt-binding/gce/mt8183-gce.h' or 'dt-bindings/gce/mt6779-gce.h'. Such as
+'dt-binding/gce/mt8183-gce.h', 'dt-binding/gce/mt8192-gce.h' or
+'dt-bindings/gce/mt6779-gce.h'. Such as
 sub-system ids, thread priority, event ids.
 
 Example: