Improve LM implementation (#373)

- Manage end of the log packet correctly.
- Add drop count, time, and program name parsing.
- Use the correct buffer type. (0x21 not 0x9)
- Prefix unknown fields with "Field"

Ryujinx.HLE/HOS/Services/Lm/LmLogField.cs

@@ -2,12 +2,17 @@ namespace Ryujinx.HLE.HOS.Services.Lm
 {
     enum LmLogField
     {
-        Skip     = 1,
-        Message  = 2,
-        Line     = 3,
-        Filename = 4,
-        Function = 5,
-        Module   = 6,
-        Thread   = 7
+        Start       = 0,
+        Stop        = 1,
+        Message     = 2,
+        Line        = 3,
+        Filename    = 4,
+        Function    = 5,
+        Module      = 6,
+        Thread      = 7,
+        DropCount   = 8,
+        Time        = 9,
+        ProgramName = 10,
+        Count
     }
 }