pciconf: Fix up pciconf -lc output

The pciconf command fails to emit newlines when particular ecap field
values are seen. Fix them up. This has been seen on several systems at
$JOB. The documentation for PCI capabilities says that capability
type 0 should not be used once the spec for PCI capabilities was
published, but that seems more wishful-thinking than reality. pciconf
also chooses not to print fields related to field values that are
zero, but it seems several of these fields are zero on actual
hardware.

Reviewed by: vangyzen, imp, Bret Ketchum (Bret.Ketchum@dell.com)
Sponsored by: Dell EMC Isilon
Submitted by: Robert Herndon (Robert.Herndon@dell.com)
Differential Revision: https://reviews.freebsd.org/D30441