dma_buf_ops are not supposed to change at runtime. All functions
working with dma_buf_ops provided by <linux/dma-buf.h> work with
const dma_buf_ops. So mark the non-const structs as const.
File size before:
text data bss dec hex filename
2002 112 0 2114 842 drivers/gpu/drm/udl/udl_dmabuf.o
File size After adding 'const':
text data bss dec hex filename
2114 0 0 2114 842 drivers/gpu/drm/udl/udl_dmabuf.o