ARM: dts: armada-39x.dtsi: Add definitions for PCIe legacy INTx interrupts
Add definitions for PCIe legacy INTx interrupts.
This is required for example in a scenario where a driver requests only
one of the legacy interrupts (INTA). Without this, the driver would be
notified on events on all 4 (INTA, INTB, INTC, INTD), even if it
requested only one of them.