net: Revert "ipv4: fix a deadlock in ip_ra_control"

This reverts commit 1215e51e.
Since raw_close() is used on every RAW socket destruction,
the changes made by 1215e51e scale sadly. This clearly
seen on endless unshare(CLONE_NEWNET) test, and cleanup_net()
kwork spends a lot of time waiting for rtnl_lock() introduced
by this commit.

Previous patch moved IP_ROUTER_ALERT out of rtnl_lock(),
so we revert this patch.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>