ARM: dts: imx6qdl-zii-rdu2: Fix accelerometer interrupt-names

According to Documentation/devicetree/bindings/iio/accel/mma8452.txt,
the correct interrupt-names are "INT1" and "INT2", so fix them
accordingly.

While at it, modify the node to only specify "INT2" since providing
two interrupts is not necessary or useful (the driver will only use
one).

Signed-off-by: Fabio Estevam <festevam@gmail.com>
[andrew.smirnov@gmail.com modified the patch to drop INT1]
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>