hdb: read_master_key use free_master_key on error

If an error occurs during read_masker_key() processing, use
free_master_key() to perform cleanup.

Change-Id: Idc0ad0131ea4855207232e9773772106cb4f5945

lib/hdb/mkey.c

@@ -147,12 +147,8 @@ read_master_keytab(krb5_context context, const char *filename,
   out:
     krb5_kt_close(context, id);
     if (ret) {
-	/* do not return allocated memory on failure */
-	do {
-	    p = (*mkey)->next;
-	    free(*mkey);
-	    *mkey = p;
-	} while (p != NULL);
+	hdb_free_master_key(context, *mkey);
+	*mkey = NULL;
     }
     return ret;
 }