PCI: Remove unused pci_printk()

include/linux/pci.h provides low-level pci_printk() interface that is
not used since the commits fab874e1 ("PCI/AER: Descope pci_printk()
to aer_printk()") and 588021b2 ("PCI: shpchp: Remove 'shpchp_debug'
module parameter"). PCI logging should not use pci_printk() but pci_*()
wrappers that follow the usual logging wrapper patterns.

Remove pci_printk().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20250407101215.1376-1-ilpo.jarvinen@linux.intel.com