ARM: dts: lpc4357-ea4357: add mma7455 i2c accelerometer

Add Freescale MMA7455 3-axis I2C accelerometer as found on
Embedded Artists' LPC4357 Developer's Kit to the device tree.

This makes it possible to access the accelerometer through
the API provided by IIO.

Signed-off-by: Joachim Eastwood <manabian@gmail.com>