sh: modify NR_IRQS from 256 to 512

Newer parts need NR_IRQS > 256, so simply bump this up to 512 across the
board. At this point sparseirq is used unconditionally across all CPUs,
so this introduces minimal overhead.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/include/asm/irq.h

@@ -9,7 +9,7 @@
  * advised to cap this at the hard limit that they're interested in
  * through the machvec.
  */
-#define NR_IRQS			256
+#define NR_IRQS			512
 #define NR_IRQS_LEGACY		8	/* Legacy external IRQ0-7 */
 
 /*