iwlwifi: re-attach to build after updates

While the build-breaking changes were only in the window of
the two commits, 3e1f5cc9a81a..9af1bba44e1c, further updates
restored some functionality as well. Now that we are done,
add iwlwifi back to the build.

This reverts commit b75d1ce6c10652fc4bfbf509deeae0e05c3d1356.

Sponsored by: The FreeBSD Foundation
MFC after: 3 days