iio: accel: Add support for the h3lis331dl accelerometer

This commit adds support for STMicroelectronics h3lis331dl high-g
accelerometer. The datasheet for this device can be found here:

http://www.st.com/web/en/resource/technical/document/
datasheet/DM00053090.pdf

Signed-off-by: Tiberiu Breana <tiberiu.a.breana@intel.com>
Reviewed-by: Denis Ciocca <denis.ciocca@st.com>
Acked-by: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>