include/linux/pci.h provides low-level pci_printk() interface that is
not used since the commits fab874e12593 ("PCI/AER: Descope pci_printk()
to aer_printk()") and 588021b28642 ("PCI: shpchp: Remove 'shpchp_debug'
module parameter"). PCI logging should not use pci_printk() but pci_*()
wrappers that follow the usual logging wrapper patterns.