irq/generic-chip: Provide irq_free_generic_chip()

Currently there's no way for users of irq_alloc_generic_chip() to free
the allocated memory other than calling kfree() manually on the
returned pointer. This may lead to errors if the internals of
irq_alloc_generic_chip() ever change. Provide a routine to free the
generic chip.
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-doc@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Link: http://lkml.kernel.org/r/1496246820-13250-2-git-send-email-brgl@bgdev.pl

include/linux/irq.h

@@ -22,6 +22,7 @@
 #include <linux/topology.h>
 #include <linux/wait.h>
 #include <linux/io.h>
+#include <linux/slab.h>
 
 #include <asm/irq.h>
 #include <asm/ptrace.h>
@@ -973,6 +974,11 @@ int __irq_alloc_domain_generic_chips(struct irq_domain *d, int irqs_per_chip,
 					 handler, clr, set, flags);	\
 })
 
+static inline void irq_free_generic_chip(struct irq_chip_generic *gc)
+{
+	kfree(gc);
+}
+
 static inline struct irq_chip_type *irq_data_get_chip_type(struct irq_data *d)
 {
 	return container_of(d->chip, struct irq_chip_type, chip);