mfd: twl6040: Convert to use regmap_irq

With regmap_irq it is possible to remove the twl6040-irq.c file and
simplify the code.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 3f2187a..34242ca 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -321,10 +321,10 @@
 
 config TWL6040_CORE
 	bool "Support for TWL6040 audio codec"
-	depends on I2C=y && GENERIC_HARDIRQS
+	depends on I2C=y
 	select MFD_CORE
 	select REGMAP_I2C
-	select IRQ_DOMAIN
+	select REGMAP_IRQ
 	default n
 	help
 	  Say yes here if you want support for Texas Instruments TWL6040 audio