LU-1346 libcfs: cleanup libcfs atomic primitives

Only libcfs/ directory are converted yet. Other directories
are left for later patches.

Signed-off-by: Liu Xuezhao <xuezhao.liu@emc.com>
Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Change-Id: Ic379ac493ca4ead1ee6aa8aeb52b4017ee65c93c
Reviewed-on: http://review.whamcloud.com/6959
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Keith Mannthey <keith.mannthey@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>