drm/ttm: Remove reference to the mem_glob member

It was removed in:

Author: Christian König <christian.koenig@amd.com>
Date:   Wed Sep 25 11:38:50 2019 +0200

    drm/ttm: remove pointers to globals
Signed-off-by: Maya Rashish <coypu@sdf.org>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/360750/Signed-off-by: Christian König <christian.koenig@amd.com>

include/drm/ttm/ttm_bo_driver.h

@@ -390,7 +390,6 @@ struct ttm_bo_driver {
 /**
  * struct ttm_bo_global - Buffer object driver global data.
  *
- * @mem_glob: Pointer to a struct ttm_mem_global object for accounting.
  * @dummy_read_page: Pointer to a dummy page used for mapping requests
  * of unpopulated pages.
  * @shrink: A shrink callback object used for buffer object swap.