drm/omap: add statics to a few structs

Some static structs are not marked as static. Add it.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
index ac74d1b..0682cb5 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
@@ -178,7 +178,7 @@
 	return omap_gem_mmap_obj(obj, vma);
 }
 
-struct dma_buf_ops omap_dmabuf_ops = {
+static struct dma_buf_ops omap_dmabuf_ops = {
 		.map_dma_buf = omap_gem_map_dma_buf,
 		.unmap_dma_buf = omap_gem_unmap_dma_buf,
 		.release = omap_gem_dmabuf_release,