kmap_atomic() has been deprecated in favor of kmap_local_page().

kmap_atomic() disables page-faults and preemption (the latter
only for !PREEMPT_RT kernels).The code between the mapping and
un-mapping in this patch does not depend on the above-mentioned
side effects.So simply replaced kmap_atomic() with kmap_local_page().
Signed-off-by: Chen Haonan <chen.haonan2@zte.com.cn>
[ rjw: Subject edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>