device: Fix property getters for id and name

When Device is created with a custom value for either.

Due to typos the getters ended up recursing until stack overflow.

src/frida.vala

@@ -485,15 +485,15 @@ namespace Frida {
 		public string id {
 			get {
 				if (_id != null)
-					return id;
+					return _id;
 				return provider.id;
 			}
 		}
 
 		public string name {
 			get {
 				if (_name != null)
-					return name;
+					return _name;
 				return provider.name;
 			}
 		}