busses/pci/ecam: add

Change-Id: I8decef75a2d7f30bb5d45fc4774037d6a92bc161
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6223
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>