LinuxKPI: add pci_err()

Add pci_err() as a wrapper to dev_err() as needed by an updated driver.

Sponsored by: The FreeBSD Foundation
Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D46660

(cherry picked from commit 01e1131e4a20ea377d580ecce210aa86726e71c6)