bonding: convert primary_slave to use RCU

This is necessary mainly for two bonding call sites: procfs and
sysfs as it was dereferenced without any real protection.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/bonding/bond_main.c
Simple merge

diff --cc drivers/net/bonding/bond_netlink.c
Simple merge

diff --cc drivers/net/bonding/bond_options.c
Simple merge

diff --cc drivers/net/bonding/bond_procfs.c
Simple merge

diff --cc drivers/net/bonding/bond_sysfs.c
Simple merge

diff --cc drivers/net/bonding/bonding.h
Simple merge