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/include/asm/mach/arch.h

@@ -20,6 +20,7 @@ struct machine_desc {
 	 * by assembler code in head.S, head-common.S
 	 */
 	unsigned int		nr;		/* architecture number	*/
+	unsigned int		nr_irqs;	/* number of IRQs */
 	unsigned int		phys_io;	/* start of physical io	*/
 	unsigned int		io_pg_offst;	/* byte offset for io 
 						 * page tabe entry	*/