[ARM] MXC: remove dependency to other include files from irqs.h

This patch removes the inclusion of mach/hardware.h from mach/irqs.h and
switches to more meaningful names for the irq related macros.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/arch/arm/plat-mxc/include/mach/iomux-mx3.h b/arch/arm/plat-mxc/include/mach/iomux-mx3.h
index 20e5c4c..c9198c0 100644
--- a/arch/arm/plat-mxc/include/mach/iomux-mx3.h
+++ b/arch/arm/plat-mxc/include/mach/iomux-mx3.h
@@ -141,7 +141,7 @@
 	((iomux_pin & IOMUX_GPIONUM_MASK) >> IOMUX_GPIONUM_SHIFT)
 #define IOMUX_TO_IRQ(iomux_pin) \
 	(((iomux_pin & IOMUX_GPIONUM_MASK) >> IOMUX_GPIONUM_SHIFT) + \
-	MXC_GPIO_INT_BASE)
+	MXC_GPIO_IRQ_START)
 
 /*
  * This enumeration is constructed based on the Section