[NET]: Remove __ARGS from include/net/slhc_vj.h

I suspect "#define __ARGS(x) ()" was deprecated before I was born.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Domen Puncer <domen@coderock.org>
Signed-off-by: David S. Miller <davem@davemloft.net>