[NUI] Fix build warning CS1064

https://docs.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca1064
CA1064: Exceptions should be public

diff --git a/src/Tizen.NUI/src/internal/XamlBinding/InvalidNavigationException.cs b/src/Tizen.NUI/src/internal/XamlBinding/InvalidNavigationException.cs
deleted file mode 100755 (executable)
index 2bdb665..0000000
--- a/src/Tizen.NUI/src/internal/XamlBinding/InvalidNavigationException.cs
+++ /dev/null
@@ -1,11 +0,0 @@
-using System;
-
-namespace Tizen.NUI.Binding
-{
-    internal class InvalidNavigationException : Exception
-    {
-        public InvalidNavigationException(string message) : base(message)
-        {
-        }
-    }
-}