[SCTP]: Clean up naming conventions of sctp protocol/address family registration

I noticed while looking into some odd behavior in sctp, that the variable
name sctp_pf_inet6_specific was used twice to represent two different
pieces of data (its both a structure name and a pointer to that type of
structure), which is confusing to say the least, and potentially dangerous
depending on the variable scope.  This patch cleans that up, and makes the
protocol and address family registration names in SCTP more regular,
increasing readability.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>

 ipv6.c     |   12 ++++++------
 protocol.c |   12 ++++++------
 2 files changed, 12 insertions(+), 12 deletions(-)