drm/ttm/tests: Add tests for ttm_bo functions

Test reservation and release of TTM buffer objects. Add tests to check
pin and unpin operations.
Signed-off-by: Karolina Stolarek <karolina.stolarek@intel.com>
Tested-by: Amaranath Somalapuram <Amaranath.Somalapuram@amd.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/fcd53970f55ae4be8c738e03f9fcf45366d20b47.1701257386.git.karolina.stolarek@intel.comSigned-off-by: Christian König <christian.koenig@amd.com>

drivers/gpu/drm/ttm/tests/Makefile

@@ -5,4 +5,5 @@ obj-$(CONFIG_DRM_TTM_KUNIT_TEST) += \
         ttm_pool_test.o \
         ttm_resource_test.o \
         ttm_tt_test.o \
+        ttm_bo_test.o \
         ttm_kunit_helpers.o

drivers/gpu/drm/ttm/tests/ttm_kunit_helpers.c

@@ -22,6 +22,10 @@ static void ttm_tt_simple_destroy(struct ttm_device *bdev, struct ttm_tt *ttm)
 	kfree(ttm);
 }
 
+static void dummy_ttm_bo_destroy(struct ttm_buffer_object *bo)
+{
+}
+
 struct ttm_device_funcs ttm_dev_funcs = {
 	.ttm_tt_create = ttm_tt_simple_create,
 	.ttm_tt_destroy = ttm_tt_simple_destroy,
@@ -61,6 +65,8 @@ struct ttm_buffer_object *ttm_bo_kunit_init(struct kunit *test,
 	KUNIT_ASSERT_EQ(test, err, 0);
 
 	bo->bdev = devs->ttm_dev;
+	bo->destroy = dummy_ttm_bo_destroy;
+
 	kref_init(&bo->kref);
 
 	return bo;