To configure the signals as PCI INTx it is needed to refer to the following documents:
1) Linux Documentation "Generic PCI Host Controller":
sdk/linux.git - Freescale PowerPC Linux Tree
2) "Open Firmware Recommended Practice: Interrupt Mapping":
http://www.firmware.org/1275/practice/imap/imap0_9d.pdf
3) P2020 interrupt mapping DTS from the Linux SDK:
sdk/linux.git - Freescale PowerPC Linux Tree
To configure the signals as IRQn it is needed to refer to the AN5121 - Introduction to Device Trees, 5 Interrupts:
http://cache.nxp.com/assets/documents/data/en/application-notes/AN5125.pdf