MAINTAINERS: Add myself to list of SCTP maintainers

MAINTAINERS: Add myself to list of SCTP maintainers

I've been messing with the code for a bit, and I figured Vlad could use a hand
as interest in the protocol has picked up over the last year or so.  I've asked
him, and he doesn't seem too upset over the idea :)

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Vlad Yasevich <vyasevich@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: linux-sctp@vger.kernel.org
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>