drm: remove unused #include <linux/version.h>'s

Remove unused #include <linux/version.h>('s) in
 drivers/gpu/drm/ttm/ttm_bo_util.c
 drivers/gpu/drm/ttm/ttm_bo_vm.c
 drivers/gpu/drm/ttm/ttm_tt.c
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/ttm/ttm_bo_util.c

@@ -34,7 +34,6 @@
 #include <linux/highmem.h>
 #include <linux/wait.h>
 #include <linux/vmalloc.h>
-#include <linux/version.h>
 #include <linux/module.h>
 
 void ttm_bo_free_old_node(struct ttm_buffer_object *bo)

drivers/gpu/drm/ttm/ttm_bo_vm.c

@@ -32,7 +32,6 @@
 #include <ttm/ttm_bo_driver.h>
 #include <ttm/ttm_placement.h>
 #include <linux/mm.h>
-#include <linux/version.h>
 #include <linux/rbtree.h>
 #include <linux/module.h>
 #include <linux/uaccess.h>

drivers/gpu/drm/ttm/ttm_tt.c

@@ -28,7 +28,6 @@
  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
  */
 
-#include <linux/version.h>
 #include <linux/vmalloc.h>
 #include <linux/sched.h>
 #include <linux/highmem.h>