[PATCH] Add rtas_set_indicator_fast() for RTAS call without extended delay

[Nathan Lynch]

Paul Mackerras wrote:
> Haren Myneni writes:
> 
> > +	WARN_ON(rc == -2 || (rc >= 9900 && rc <= 9905));
> 
> This worries me... do we know for sure that RTAS will never return a
> busy code?  If it could possibly return a busy code, and we can't
> sleep, then we should spin doing the call again and again until it
> works, I think.

The PAPR marks certain RTAS calls as "fast", meaning they must not
return any kind of busy status.  Manipulating the GIQ (set-indicator
with token 9005) is defined as "fast".