ikev2: Remove private AUTH_BLISS method

We use the new signature authentication instead for this.  This is not
backward compatible but we only released one version with BLISS support,
and the key format will change anyway with the next release.

src/libcharon/sa/authenticator.h

@@ -89,11 +89,6 @@ enum auth_method_t {
 	 */
 	AUTH_DS = 14,
 
-	/**
-	 * BLISS Authentication Method
-	 */
-	AUTH_BLISS = 220,
-
 	/**
 	 * IKEv1 initiator XAUTH with PSK, outside of IANA range
 	 */