PCI: pci-bridge-emul: Make struct pci_bridge_emul_ops as const

It is read-only constant structure, so properly mark it with const keyword.

Link: https://lore.kernel.org/r/20220104153529.31647-3-pali@kernel.org


Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>