On MIPS we want to call of_irq_map_pci from inside

arch/mips/include/asm/pci.h:extern int pcibios_map_irq(
				const struct pci_dev *dev, u8 slot, u8 pin);
For this to work we need to change several functions to const usage.
Signed-off-by: NJohn Crispin <blogic@openwrt.org>
Cc: linux-pci@vger.kernel.org
Cc: devicetree-discuss@lists.ozlabs.org
Cc: linux-mips@linux-mips.org
Acked-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NGrant Likely <grant.likely@secretlab.ca>
Patchwork: https://patchwork.linux-mips.org/patch/3710/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>