ttm_place are not supposed to change at runtime. All functions
working with ttm_place provided by <drm/ttm/ttm_placement.h> work
with const ttm_place. So mark the non-const structs as const.
File size before:
text data bss dec hex filename
3485 184 264 3933 f5d drivers/gpu/drm/qxl/qxl_ttm.o
File size After adding 'const':
text data bss dec hex filename
3501 152 264 3917 f4d drivers/gpu/drm/qxl/qxl_ttm.o