[PATCH] add {request,free}_virt_irq() helper functions

[Paul Mackerras]

Nishanth Aravamudan writes:

> +int request_virt_irq(__u32 ist, 
> +		     irqreturn_t (*handler)(int, void*, struct pt_regs *),
> +		     unsigned long irq_flags, const char * devname,
> +		     void *dev_id)

Baaaad name.  This isn't at all about requesting a virtual IRQ, in
fact request_irq already does that.  This interface needs to be
rethought.

Paul.