PCI: Make pci_assign_unassigned_resources() non-init

Fix a section mismatch warning on Sparc 32-bit:

  WARNING: modpost: vmlinux: section mismatch in reference: leon_pci_init+0xf8 (section: .text) -> pci_assign_unassigned_resources (section: .init.text)

This is due to this comment from arch/sparc/kernel/leon_pci.c:

  The LEON architecture does not rely on a BIOS or bootloader to setup PCI
  for us. The Linux generic routines are used to setup resources, reset
  values of configuration-space register settings are preserved.

Link: https://lore.kernel.org/r/20230925042316.15415-1-rdunlap@infradead.org


Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: sparclinux@vger.kernel.org