ARM: ux500: fix lsm303dlh magnetometer compat string

The magnetometer found on the Ux500 TVK and Snowball boards
is a LSM303DLH not a LSM303DLM, small differences but still
different. Put in the right compatible strings and things start
working smoothly.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>