sys: Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Fix some modules to export more used symbols

and remove non-present symbols that are now reported by kmod_syms.awk.

Reviewed by: emaste
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D32878

Factor out generic IP over infiniband, IPoIB, definitions and code
into net/if_infiniband.c and net/infiniband.h . No functional change
intended.

Differential Revision: https://reviews.freebsd.org/D26254
Reviewed by: melifaro@
MFC after: 1 week
Sponsored by: Mellanox Technologies // NVIDIA Networking