ARM: mxs: move icoll driver into drivers/irqchip

Move icoll.c into drivers/irqchip as irq-mxs.c, and along with the
renaming, change the driver to use IRQCHIP_DECLARE.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

include/linux/irqchip/mxs.h

@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) 2013 Freescale Semiconductor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __LINUX_IRQCHIP_MXS_H
+#define __LINUX_IRQCHIP_MXS_H
+
+extern void icoll_handle_irq(struct pt_regs *);
+
+#endif