drm: init TTM dev_mapping in ttm_bo_device_init()

With dev->anon_inode we have a global address_space ready for operation
right from the beginning. Therefore, there is no need to do a delayed
setup with TTM. Instead, set dev_mapping during initialization in
ttm_bo_device_init() and remove any "if (dev_mapping)" conditions.

Cc: Dave Airlie <airlied@redhat.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Alex Deucher <alexdeucher@gmail.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

drivers/gpu/drm/bochs/bochs_mm.c

@@ -225,7 +225,9 @@ int bochs_mm_init(struct bochs_device *bochs)
 
 	ret = ttm_bo_device_init(&bochs->ttm.bdev,
 				 bochs->ttm.bo_global_ref.ref.object,
-				 &bochs_bo_driver, DRM_FILE_PAGE_OFFSET,
+				 &bochs_bo_driver,
+				 bochs->dev->anon_inode->i_mapping,
+				 DRM_FILE_PAGE_OFFSET,
 				 true);
 	if (ret) {
 		DRM_ERROR("Error initialising bo driver; %d\n", ret);