PCI/MSI: Add pci_msi_map_rid_ctlr_node() helper function

PCI/MSI: Add pci_msi_map_rid_ctlr_node() helper function

IRQchip drivers need a PCI/MSI function to map a RID to a MSI
controller deviceID namespace and at the same time retrieve the
struct device_node pointer of the MSI controller the RID is mapped
to.

Add pci_msi_map_rid_ctlr_node() to achieve this purpose.

Cc  Bjorn Helgaas <bhelgaas@google.com>

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250703-gicv5-host-v7-25-12e71f1b3528@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>