Merge branch 'ipv6_null'

Ian Morris says:

====================
ipv6: coding style - comparisons with NULL

The following patches address some coding style issues only. No
functional changes and no changes detected by objdiff.

The IPV6 code uses multiple different styles when comparing with NULL
(I.e. x == NULL and !x as well as x != NULL and x). Generally the
latter form is preferred according to checkpatch and so this changes
aligns the code to this style.
====================

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