Remove reference to DSA and rename KM_ALGORITHM_ECDSA.

Change-Id: Ibffddc5c3a5c728182f5ca7f6a76381413fc8645
diff --git a/ec_key.h b/ec_key.h
index 2ed789c..0d57e0d 100644
--- a/ec_key.h
+++ b/ec_key.h
@@ -44,7 +44,7 @@
 
 class EcdsaKeyFactory : public EcKeyFactory {
   public:
-    virtual keymaster_algorithm_t registry_key() const { return KM_ALGORITHM_ECDSA; }
+    virtual keymaster_algorithm_t registry_key() const { return KM_ALGORITHM_EC; }
 };
 
 class EcdsaSignOperationFactory;