drivers: gpu: Mark functions as static in mgag200_ttm.c

Mark functions mgag200_ttm_global_release(),
mgag200_ttm_bo_is_mgag200_bo() and mgag200_ttm_tt_create() as static in
drm/mgag200/mgag200_ttm.c because they are not used outside this file.

This eliminates the following warning in drm/mgag200/mgag200_ttm.c:
drivers/gpu/drm/mgag200/mgag200_ttm.c:84:1: warning: no previous prototype for ‘mgag200_ttm_global_release’ [-Wmissing-prototypes]
drivers/gpu/drm/mgag200/mgag200_ttm.c:105:6: warning: no previous prototype for ‘mgag200_ttm_bo_is_mgag200_bo’ [-Wmissing-prototypes]
drivers/gpu/drm/mgag200/mgag200_ttm.c:211:16: warning: no previous prototype for ‘mgag200_ttm_tt_create’ [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <[e-mail]>
Reviewed-by: Josh Triplett <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

drivers/gpu/drm/mgag200/mgag200_ttm.c

···
 	return 0;
 }
 
-void
+static void
 mgag200_ttm_global_release(struct mga_device *ast)
 {
 	if (ast->ttm.mem_global_ref.release == NULL)
···
 	kfree(bo);
 }
 
-bool mgag200_ttm_bo_is_mgag200_bo(struct ttm_buffer_object *bo)
+static bool mgag200_ttm_bo_is_mgag200_bo(struct ttm_buffer_object *bo)
 {
 	if (bo->destroy == &mgag200_bo_ttm_destroy)
 		return true;
···
 };
 
 
-struct ttm_tt *mgag200_ttm_tt_create(struct ttm_bo_device *bdev,
+static struct ttm_tt *mgag200_ttm_tt_create(struct ttm_bo_device *bdev,
 				 unsigned long size, uint32_t page_flags,
 				 struct page *dummy_read_page)
 {