feat(plat/mediatek/mt8195): add vcore-dvfs support

Add DVFSRC init flow.

Change-Id: Ic5fc78c91359abc12c0f54b01860a7cbe41f3358
diff --git a/plat/mediatek/mt8195/include/platform_def.h b/plat/mediatek/mt8195/include/platform_def.h
index b84e73f..a287333 100644
--- a/plat/mediatek/mt8195/include/platform_def.h
+++ b/plat/mediatek/mt8195/include/platform_def.h
@@ -31,6 +31,7 @@
 #define VPPSYS1_BASE            (IO_PHYS + 0x04f00000)
 #define VDOSYS0_BASE            (IO_PHYS + 0x0C01A000)
 #define VDOSYS1_BASE            (IO_PHYS + 0x0C100000)
+#define DVFSRC_BASE             (IO_PHYS + 0x00012000)
 
 /*******************************************************************************
  * DP/eDP related constants