dlm: remove unused variable in *dlm_lowcomms_get_buffer()

The variable users is initialized but never used
otherwise, so remove the unused variable.

dpatch engine is used to auto generate this patch.
(https://github.com/weiyj/dpatch

)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David Teigland <teigland@redhat.com>