dt-bindings: soc: Add clocks for Mediatek SCPSYS unit

Add clocks needed by Mediatek VENC and VENC_LT power domianis.
These clocks were needed by accessing subsystem's registers,
so they need to be enabled before power on these subsystems.
Signed-off-by: NJames Liao <jamesjj.liao@mediatek.com>
Signed-off-by: NMatthias Brugger <matthias.bgg@gmail.com>

Documentation/devicetree/bindings/soc/mediatek/scpsys.txt

@@ -17,9 +17,9 @@ Required properties:
 - reg: Address range of the SCPSYS unit
 - infracfg: must contain a phandle to the infracfg controller
 - clock, clock-names: clocks according to the common clock binding.
-                      The clocks needed "mm" and "mfg". These are the
-		      clocks which hardware needs to be enabled before
-		      enabling certain power domains.
+                      The clocks needed "mm", "mfg", "venc" and "venc_lt".
+		      These are the clocks which hardware needs to be enabled
+		      before enabling certain power domains.
 
 Example:
 
@@ -30,7 +30,9 @@ Example:
 		infracfg = <&infracfg>;
 		clocks = <&clk26m>,
 			 <&topckgen CLK_TOP_MM_SEL>;
-		clock-names = "mfg", "mm";
+			 <&topckgen CLK_TOP_VENC_SEL>,
+			 <&topckgen CLK_TOP_VENC_LT_SEL>;
+		clock-names = "mfg", "mm", "venc", "venc_lt";
 	};
 
 Example consumer: