FiX build when Ethernet is included (#6)

The macro `MBED_DEPRECATED` only takes one argument. Also move it to
ensure the class is marked deprecated correctly.

Author: hugueskamba

drivers/Ethernet.h

@@ -61,12 +61,12 @@ namespace mbed {
  * }
  * @endcode
  */
+class 
 MBED_DEPRECATED(
-    "EthInterface is now the preferred way to get an Ethernet object.",
-    "Alternatively, use NetworkInterface to get an instance of an appropriate network"
+    "EthInterface is now the preferred way to get an Ethernet object. "
+    "Alternatively, use NetworkInterface to get an instance of an appropriate network "
     "interface (WiFi or Ethernet)."
-)
-class Ethernet : private NonCopyable<Ethernet> {
+) Ethernet : private NonCopyable<Ethernet> {
 
 public: