PCI: Move PCI-specific devres code to drivers/pci/

PCI: Move PCI-specific devres code to drivers/pci/

The pcim_*() functions in lib/devres.c are guarded by an #ifdef CONFIG_PCI
and, thus, don't belong to this file. They are only ever used for PCI and
are not generic infrastructure.

Move all pcim_*() functions in lib/devres.c to drivers/pci/devres.c.
Adjust the Makefile.

Add drivers/pci/devres.c to Documentation.

Link: https://lore.kernel.org/r/20240131090023.12331-4-pstanner@redhat.com
Suggested-by: Danilo Krummrich <dakr@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>