ARM: dts: imx6qdl-gw591: Remove lis2de12 interrupt-names

ARM: dts: imx6qdl-gw591: Remove lis2de12 interrupt-names

According to st,st-sensors.yaml, the 'interrupt-names' property is
not a valid one.

Remove it to fix the following schema warnings:

imx6dl-gw5912.dtb: accel@19: 'interrupt-names' does not match any of the regexes: 'pinctrl-[0-9]+'
	from schema $id: http://devicetree.org/schemas/iio/st,st-sensors.yaml#

Signed-off-by: Fabio Estevam <festevam@denx.de>
Acked-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>