net: percpu_counter_inc() should not be called in BH-disabled section

Based upon a lockdep report by Alexey Dobriyan.

I checked all per_cpu_counter_xxx() usages in network tree, and I
think all call sites are BH enabled except one in
inet_csk_listen_stop().

commit dd24c001
(net: Use a percpu_counter for orphan_count)
replaced atomic_t orphan_count to a percpu_counter.

atomic_inc()/atomic_dec() can be called from any context, while
percpu_counter_xxx() should be called from a consistent state.

For orphan_count, this context can be the BH-enabled one.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>