treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

iio: imu: Add initial support for Bosch BMI160

BMI160 is an Inertial Measurement Unit (IMU) which provides acceleration
and angular rate measurement. It also offers a secondary I2C interface
for connecting a magnetometer sensor (usually BMM160).

Current driver offers support for accelerometer and gyroscope readings
via sysfs or via buffer interface using an external trigger (e.g.
hrtimer). Data is retrieved from IMU via I2C or SPI interface.

Datasheet is at:
http://www.mouser.com/ds/2/783/BST-BMI160-DS000-07-786474.pdf

Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>