ARM: 6197/2: preliminary support for sparse IRQ

So to allow NR_IRQS to be dynamic and platforms to specify the number
of IRQs really needed.

Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/setup.c

@@ -729,6 +729,7 @@ void __init setup_arch(char **cmdline_p)
 	/*
 	 * Set up various architecture-specific pointers
 	 */
+	arch_nr_irqs = mdesc->nr_irqs;
 	init_arch_irq = mdesc->init_irq;
 	system_timer = mdesc->timer;
 	init_machine = mdesc->init_machine;