powerpc/5200: dts: digsy_mtc.dts: update to add can, pci, serial and spi
Add new nodes to describe more hardware the board is
equipped with:
- two can nodes for SJA1000 on localbus
- pci node to support Coral-PA graphics controller
- serial node for SC28L92 DUART on localbus
- spi node for MSP430 device