ARM: dts: imx6qdl-gw553x: add lsm9ds1 iio imu/magn support

Add one node for the accel/gyro i2c device and another for the separate
magnetometer device in the lsm9ds1.

Signed-off-by: Robert Jones <rjones@gateworks.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>