Input: edt-ft5x06 - do not hardcode interrupt trigger type

Instead of hardcoding IRQ trigger type to IRQF_TRIGGER_FALLING, let's
respect settings specified in device tree. To be compatible with older
DTSes, if trigger type is not set up in DTS we'll set it to default
(falling edge).

Tested-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt

@@ -49,7 +49,7 @@ Example:
 		pinctrl-names = "default";
 		pinctrl-0 = <&edt_ft5x06_pins>;
 		interrupt-parent = <&gpio2>;
-		interrupts = <5 0>;
+		interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
 		reset-gpios = <&gpio2 6 GPIO_ACTIVE_LOW>;
 		wake-gpios = <&gpio4 9 GPIO_ACTIVE_HIGH>;
 	};