ipvs: remove _bh from percpu stats reading

 	ip_vs_read_cpu_stats is called only from timer, so
no need for _bh locks.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: Simon Horman <horms@verge.net.au>