Minor improvements in code style

Author: josesimoes

System.Device.I2c/I2cConnectionSettings.cs

@@ -10,14 +10,14 @@ namespace System.Device.I2c
     public sealed class I2cConnectionSettings
     {
 
-        [System.Diagnostics.DebuggerBrowsable(System.Diagnostics.DebuggerBrowsableState.Never)]
-        private int _deviceAddress;
+        [Diagnostics.DebuggerBrowsable(Diagnostics.DebuggerBrowsableState.Never)]
+        private readonly int _deviceAddress;
 
-        [System.Diagnostics.DebuggerBrowsable(System.Diagnostics.DebuggerBrowsableState.Never)]
-        private I2cBusSpeed _busSpeed;
+        [Diagnostics.DebuggerBrowsable(Diagnostics.DebuggerBrowsableState.Never)]
+        private readonly I2cBusSpeed _busSpeed;
 
-        [System.Diagnostics.DebuggerBrowsable(System.Diagnostics.DebuggerBrowsableState.Never)]
-        private int _busId;
+        [Diagnostics.DebuggerBrowsable(Diagnostics.DebuggerBrowsableState.Never)]
+        private readonly int _busId;
 
         private I2cConnectionSettings()
         { }