gpio: tc3589x: use gpiolib irqchip helpers

Now that the gpiolib irqchip helpers can support nested, threaded
IRQ handlers, switch the TC3589x driver over to using this new
infrastructure. Tested on the Ux500.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index a86c49a..5ad9e92 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -579,6 +579,7 @@
 config GPIO_TC3589X
 	bool "TC3589X GPIOs"
 	depends on MFD_TC3589X
+	select GPIOLIB_IRQCHIP
 	help
 	  This enables support for the GPIOs found on the TC3589X
 	  I/O Expander.