percpu_xxx funcs are duplicated with this_cpu_xxx funcs, so replace
them for further code clean up.

And in preempt safe scenario, __this_cpu_xxx funcs may has a bit
better performance since __this_cpu_xxx has no redundant
preempt_enable/preempt_disable on some architectures.
Signed-off-by: NAlex Shi <alex.shi@intel.com>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NTejun Heo <tj@kernel.org>