drm/ttm: remove unsued options from ttm_mem_global_alloc_page

Nobody is actually using that, remove it.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>