[ARM] Wrap calls to descriptor handlers

This is part of Thomas Gleixner's generic IRQ patch, which converts
ARM to use the generic IRQ subsystem.  Here, we wrap calls to
desc->handler() in an inline function, desc_handle_irq().  This
reduces the size of Thomas' patch since the changes become more
localised.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index 58b3bd0..3284118 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -517,7 +517,7 @@
 		list_for_each_safe(l, n, &head) {
 			desc = list_entry(l, struct irqdesc, pend);
 			list_del_init(&desc->pend);
-			desc->handle(desc - irq_desc, desc, regs);
+			desc_handle_irq(desc - irq_desc, desc, regs);
 		}
 
 		/*
@@ -545,7 +545,7 @@
 
 	irq_enter();
 	spin_lock(&irq_controller_lock);
-	desc->handle(irq, desc, regs);
+	desc_handle_irq(irq, desc, regs);
 
 	/*
 	 * Now re-run any pending interrupts.