Pull percpu updates from Tejun Heo:
 "Nothing too exciting.  percpu_ref is going through some interface
  changes and getting new features with more changes in the pipeline but
  given its young age and few users, it's very low impact"

* 'for-3.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
  percpu-refcount: implement percpu_ref_tryget()
  percpu-refcount: rename percpu_ref_tryget() to percpu_ref_tryget_live()
  percpu: Replace __get_cpu_var with this_cpu_ptr