Adding device driver inheritance mechanism.

Change-Id: I9c883d32ce0c39f961eddd5c4624dc23f794fe4d
diff --git a/core/api/src/main/java/org/onosproject/net/driver/DriverService.java b/core/api/src/main/java/org/onosproject/net/driver/DriverService.java
index fa37f1b..1a74255 100644
--- a/core/api/src/main/java/org/onosproject/net/driver/DriverService.java
+++ b/core/api/src/main/java/org/onosproject/net/driver/DriverService.java
@@ -22,7 +22,7 @@
 /**
  * Service for obtaining drivers and driver behaviour implementations.
  */
-public interface DriverService {
+public interface DriverService extends DriverResolver {
 
     /**
      * Returns the overall set of drivers being provided.
@@ -40,16 +40,6 @@
     Set<Driver> getDrivers(Class<? extends Behaviour> withBehaviour);
 
     /**
-     * Returns the specified driver.
-     *
-     * @param driverName driver name
-     * @return driver
-     * @throws org.onlab.util.ItemNotFoundException if driver with the given
-     *                                              name is not found
-     */
-    Driver getDriver(String driverName);
-
-    /**
      * Returns the driver that matches the specified primordial device
      * discovery information.
      *