arm: Move chained_irq_(enter|exit) to a generic file

These functions have been introduced by commit 10a8c383 (irq: introduce
entry and exit functions for chained handlers) in asm/mach/irq.h. This
patch moves them to linux/irqchip/chained_irq.h so that generic irqchip
drivers do not rely on architecture specific header files.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rob Herring <rob.herring@calxeda.com>
diff --git a/drivers/gpio/gpio-tegra.c b/drivers/gpio/gpio-tegra.c
index 414ad91..8e21555 100644
--- a/drivers/gpio/gpio-tegra.c
+++ b/drivers/gpio/gpio-tegra.c
@@ -27,11 +27,10 @@
 #include <linux/platform_device.h>
 #include <linux/module.h>
 #include <linux/irqdomain.h>
+#include <linux/irqchip/chained_irq.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/pm.h>
 
-#include <asm/mach/irq.h>
-
 #define GPIO_BANK(x)		((x) >> 5)
 #define GPIO_PORT(x)		(((x) >> 3) & 0x3)
 #define GPIO_BIT(x)		((x) & 0x7)