[RFC] powerpc/irq: Add generic API for setting up cascaded IRQs

[Benjamin Herrenschmidt]

> I'm a reverse polish kind of guy.  I preferring 'subject'_'action'
> over 'action'_'subject' just because it groups like subjects together.
>  But it doesn't matter much, especially in this case where 'subject'
> is in a group of exactly 1.  :-)
> 
> I'll do whichever you prefer.

I just caught myself calling something relocs_check instead of
check_relocs so I suppose it's fair game :-)

Whatever you want.

Cheers,
Ben.