arm: mx51: define mx51's own MXC_GPIO_IRQS

mx5 SoCs have different GPIO port count.
Signed-off-by: Richard Zhao <richard.zhao@freescale.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/plat-mxc/include/mach/irqs.h

@@ -29,7 +29,7 @@
 #define MXC_GPIO_IRQS		(32 * 4)
 #elif defined CONFIG_ARCH_MX25
 #define MXC_GPIO_IRQS		(32 * 4)
-#elif defined CONFIG_ARCH_MX5
+#elif defined CONFIG_ARCH_MX51
 #define MXC_GPIO_IRQS		(32 * 4)
 #elif defined CONFIG_ARCH_MXC91231
 #define MXC_GPIO_IRQS		(32 * 4)