irqchip: Remove header drivers/irqchip/irqchip.h

All drivers using the macro IRQCHIP_DECLARE have been converted to using global
header include/linux/irqchip.h. Local header drivers/irqchip/irqchip.h is now
useless and can be removed.
Signed-off-by: Joel Porquet <joel@porquet.org>
Cc: vgupta@synopsys.com
Cc: monstr@monstr.eu
Cc: ralf@linux-mips.org
Cc: jason@lakedaemon.net
Link: http://lkml.kernel.org/r/2818400.nekF4hg2Ig@joel-zenbookSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/irqchip/irqchip.h

-/*
- * Copyright (C) 2012 Thomas Petazzoni
- *
- * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
- *
- * This file is licensed under the terms of the GNU General Public
- * License version 2.  This program is licensed "as is" without any
- * warranty of any kind, whether express or implied.
- */
-
-#include <linux/irqchip.h>