iio/scmi: Adding support for IIO SCMI Based Sensors

This change provides ARM SCMI Protocol based IIO device.
This driver provides support for Accelerometer and Gyroscope using
SCMI Sensor Protocol extensions added in the SCMIv3.0 ARM specification

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jyoti Bhayana <jbhayana@google.com>
Link: https://lore.kernel.org/r/20210212172235.507028-2-jbhayana@google.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20210309231259.78050-2-jbhayana@google.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>