LinuxKPI: pci: add pci_info()

Add pci_info() needed for a driver update. While here prefix
VA_ARGS with ## for pci_err and pci_info in case we are only
passed a string without format arguments.

Sponsored by: The FreeBSD Foundation
MFC after: 3 days
Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D50009