regmap: Convert regmap_irq to use irq_domain

This gets us up to date with the recommended current kernel infrastructure
and should transparently give us device tree interrupt bindings for any
devices using the framework. If an explicit IRQ mapping is passed in then
a legacy interrupt range is created, otherwise a simple linear mapping is
used. Previously a mapping was mandatory so existing drivers should not
be affected.

A function regmap_irq_get_virq() is provided to allow drivers to map
individual IRQs which should be used in preference to the existing
regmap_irq_chip_get_base() which is only valid if a legacy IRQ range is
provided.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 9dbc9a1..7208668 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -245,6 +245,7 @@
 			struct regmap_irq_chip_data **data);
 void regmap_del_irq_chip(int irq, struct regmap_irq_chip_data *data);
 int regmap_irq_chip_get_base(struct regmap_irq_chip_data *data);
+int regmap_irq_get_virq(struct regmap_irq_chip_data *data, int irq);
 
 #else