uapi: add missing network related headers to kbuild

The makefile for sanitizing kernel headers uses the kbuild file
to determine which files to do. Several networking related headers
were missing. Without these headers iproute2 build would break.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>