LinuxKPI: pci.h add more defines and functions

Add #defines for PCI_DEVICE_ID and repoint the PCI_VENDOR_ID one.
Add dev_is_pci().
Add pcie_capability_clear_word() according to similar implementations.

Sponsored by: The FreeBSD Foundation
Reviewed by: hselasky, emaste
Differential Revision: https://reviews.freebsd.org/D36653

(cherry picked from commit c41d83548b6cf18b48af974ad995354f38cf04a4)