misc: Use official names for NVDEC registers (#4192)

* misc: Uses official names for NVDEC registers

* Address gdkchan's comment

* Address comments

Ryujinx.Graphics.Nvdec/ApplicationId.cs

@@ -0,0 +1,14 @@
+namespace Ryujinx.Graphics.Nvdec
+{
+    public enum ApplicationId
+    {
+        Mpeg = 1,
+        Vc1 = 2,
+        H264 = 3,
+        Mpeg4 = 4,
+        Vp8 = 5,
+        Hevc = 7,
+        Vp9 = 9,
+        HevcParser = 12,
+    }
+}