When booting with device-tree on an OMAP2420H4, the kernel is hanging when
initialising the interrupts and following kernel dumps is seen ...

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: at arch/arm/mach-omap2/irq.c:271 omap_intc_of_init+0x50/0xb4()
[    0.000000] unable to get intc registers
[    0.000000] Modules linked in:
[    0.000000] [<c001befc>] (unwind_backtrace+0x0/0xf4) from [<c0040c34>] (warn_slowpath_common+0x4c/0x64)
[    0.000000] [<c0040c34>] (warn_slowpath_common+0x4c/0x64) from [<c0040ce0>] (warn_slowpath_fmt+0x30/0x40)
[    0.000000] [<c0040ce0>] (warn_slowpath_fmt+0x30/0x40) from [<c066b8a4>] (omap_intc_of_init+0x50/0xb4)
[    0.000000] [<c066b8a4>] (omap_intc_of_init+0x50/0xb4) from [<c0688b70>] (of_irq_init+0x144/0x288)
[    0.000000] [<c0688b70>] (of_irq_init+0x144/0x288) from [<c0663294>] (init_IRQ+0x14/0x1c)
[    0.000000] [<c0663294>] (init_IRQ+0x14/0x1c) from [<c06607fc>] (start_kernel+0x198/0x304)
[    0.000000] [<c06607fc>] (start_kernel+0x198/0x304) from [<80008044>] (0x80008044)
[    0.000000] ---[ end trace 1b75b31a2719ed1c ]---
[    0.000000] of_irq_init: children remain, but no parents

The OMAP2 interrupt controller binding is missing the number of interrupts and
interrupt controller register address. Adding these fixes the problem.
Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>