[PATCH] i386: include linux/irq.h rather than asm/hw_irq.h

I need the following patch to compile -git8 here, otherwise these
files fail to compile (asm/hw_irq.h needs definitions from
linux/irq.h and that file provides the required include ordering).

I did not do a full audit, though there looks to be many other
places that should get the same treatment, if this is  the right
way to do it.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>