drm/xe: Fix a typo in xe_vm_doc.h

s/vm->ttm.base.resv->lock/vm->gpuvm.r_obj->resv->lock

Signed-off-by: Oak Zeng <oak.zeng@intel.com>
Reviewed-by: Maciej Patelczyk <maciej.patelczyk@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250113212324.3264218-1-oak.zeng@intel.com


Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>