[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/drivers/serial/imx.c b/drivers/serial/imx.c
index 73dea88..a509546 100644
--- a/drivers/serial/imx.c
+++ b/drivers/serial/imx.c
@@ -191,7 +191,7 @@
 #define SERIAL_IMX_MAJOR        207
 #define MINOR_START	        16
 #define DEV_NAME		"ttymxc"
-#define MAX_INTERNAL_IRQ	MXC_MAX_INT_LINES
+#define MAX_INTERNAL_IRQ	MXC_INTERNAL_IRQS
 #endif
 
 /*