Revert "pcidev.c: Factor out pcidev_validate() into pure fn"

This reverts commit e28d75ed.

This is broken in multiple ways, e.g. pcidev_init() can only return
NULL.

Change-Id: I06242147ba9d3a062d442f645eb0800ef51af19f
Signed-off-by: Nico Huber <nico.h@gmx.de>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Reported-by: Michael Bishop <cleverca22@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/38319


Reviewed-by: Angel Pons <th3fanbus@gmail.com>