The dma-ranges property was missed when adding the binding initially.
The root port can use up to 6 address translation tables, depending on
configuration.

Link: https://www.microsemi.com/document-portal/doc_download/1245812-polarfire-fpga-and-polarfire-soc-fpga-pci-express-user-guide # Section 1.3.3
Link: https://lore.kernel.org/r/20220819231415.3860210-4-mail@conchuod.ie
Fixes: 6ee6c89a ("dt-bindings: PCI: microchip: Add Microchip PolarFire host binding")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>