olimexino_stm32: Remove empty board file

Use a kbuild trick to force built-in.o to get built even if there isn't
any code so we can link properly.  This is cleaner than keeping around
files that don't do anything.

We keep around board.h for now since drivers and other code might expect
it to exist.

Change-Id: I2e824e1baf582517e713cabe1850c9accd509a5a
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>

boards/olimexino_stm32/Makefile

@@ -1,5 +1,2 @@
-ccflags-y += -I$(srctree)/include/drivers
-ccflags-y += -I$(srctree)/drivers
-asflags-y := ${ccflags-y}
-
-obj-y += board.o
+# No C files (yet)
+obj- += dummy.o

boards/olimexino_stm32/board.c

@@ -1,17 +0,0 @@
-/*
- * Copyright (c) 2016 Open-RnD Sp. z o.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "board.h"