iwlwifi: prepare to support debugfs

Import two files left out initially from the driver needed for debugfs
support [1]. Adjust the driver further to make it compile on FreeBSD.
This is currently turned off and needs more LinuxKPI/lindebugfs work.
Being in the tree will allow us to collaboratively work on it and
then we can enable it for good.

Obtained from: Linux wireless-testing (tag: wt-2022-10-19) [1]

		2c9078b9abcb884e27360340aaa7dfd4c0de29b3

Sponsored by: The FreeBSD Foundation
MFC after: 3 days