OMAP4/5 has been (ab)using the gic_arch_extn to provide
wakeup from suspend, and it makes a lot of sense to convert
this code to use stacked domains instead.

This patch does just this, updating the DT files to actually
reflect what the HW provides.

BIG FAT WARNING: because the DTs were so far lying by not
exposing the WUGEN HW block, kernels with this patch applied
won't have any suspend-resume facility when booted with old DTs,
and old kernels with updated DTs won't even boot.

On a platform with this patch applied, the system looks like
this:

root@bacon-fat:~# cat /proc/interrupts
            CPU0       CPU1
 16:          0          0     WUGEN  37  gp_timer
 19:     233799     155916       GIC  27  arch_timer
 23:          0          0     WUGEN   9  l3-dbg-irq
 24:          1          0     WUGEN  10  l3-app-irq
 27:        282          0     WUGEN  13  omap-dma-engine
 44:          0          0  4ae10000.gpio  13  DMA
294:          0          0     W...