Merge branch 'ipv6-fixes'

Hangbin Liu says:

====================
fix two kernel panics when disabled IPv6 on boot up

When disabled IPv6 on boot up, since there is no ipv6 route tables, we should
not call rt6_lookup. Fix them by checking if we have inet6_dev pointer on
netdevice.

v2: Fix idev reference leak, declarations and code mixing as Stefano,
    Eric pointed. Since we only want to check if idev exists and not
    reference it, use __in6_dev_get() insteand of in6_dev_get().
====================

Signed-off-by: David S. Miller <davem@davemloft.net>