[POWERPC] Update mpc7448hpc2 board irq support using device tree
The patch rewrites mpc7448hpc2 board irq support according to the new
mpic device tree interface.
Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
authored by