irq_domain/powerpc: Use common irq_domain structure instead of irq_host

This patch drops the powerpc-specific irq_host structures and uses the common
irq_domain strucutres defined in linux/irqdomain.h.  It also fixes all
the users to use the new structure names.

Renaming irq_host to irq_domain has been discussed for a long time, and this
patch is a step in the process of generalizing the powerpc virq code to be
usable by all architecture.

An astute reader will notice that this patch actually removes the irq_host
structure instead of renaming it.  This is because the irq_domain structure
already exists in include/linux/irqdomain.h and has the needed data members.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Milton Miller <miltonm@bga.com>
Tested-by: Olof Johansson <olof@lixom.net>
diff --git a/arch/powerpc/include/asm/ehv_pic.h b/arch/powerpc/include/asm/ehv_pic.h
index a9e1f4f..dc7d48e 100644
--- a/arch/powerpc/include/asm/ehv_pic.h
+++ b/arch/powerpc/include/asm/ehv_pic.h
@@ -25,7 +25,7 @@
 
 struct ehv_pic {
 	/* The remapper for this EHV_PIC */
-	struct irq_host	*irqhost;
+	struct irq_domain	*irqhost;
 
 	/* The "linux" controller struct */
 	struct irq_chip	hc_irq;