hwaccess_x86_io: clean header concept

Move all function implementations into the .c file

TEST: `[g]make [WARNERROR=no]` on Linux, FreeBSD, NetBSD, OpenBSD,
DragonflyBSD, OpenIndiana, Debian-GNU/Hurd

Change-Id: I1400704e9ac5fed00c096796536108d5bfb875e3
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/61276
Original-Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72308
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
4 files changed