Provide platform data for the lsm6ds3 accelerometer Linux kernel
driver since the platform data type definition did not appear to be
present in the upstream repository.

Source came from here:
https://github.com/STMicroelectronics/STMems_Linux_Input_drivers/tree/linux-3.10.y-gh/drivers/input/misc/st/imu/lsm6ds3
Last update in this revision: 2b218416b197598225c50cddc26582301cc1e91e

Ignore Developer Studio metadata files

* Remove the setup.sh script since it is not necessary if the
  --recursive option is passed to git clone.
* Correct a URL in the README.md which points to the Developer Studio
  branch of mangOH where submodule usage was proposed.

Also remove an application definition from the mangOH Red
sdef for SPI testing since the application is not published.

Remove the .gitignore entires since they are no longer relevant after
switching from repo to submodules.