arm64: dts: imx8mq-librem5-devkit: use correct interrupt for the magnetometer

The LSM9DS1 uses a high level interrupt.

Signed-off-by: Angus Ainslie (Purism) <angus@akkea.ca>
Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Fixes: eb4ea085 ("arm64: dts: fsl: librem5: Add a device tree for the Librem5 devkit")
Signed-off-by: Shawn Guo <shawnguo@kernel.org>