add missing license and copyright statements to public interface headers

add missing license and copyright statements to public interface headers

The copyright line indicates a person, a group of people and/or a company
granting rights stated in the license text and is a required part of the
license.

The year of the copyright is chosen to be the same as when the license has
been applied to the file or when the file has been created in case there
was no license.  It is possible to update or add additional years if major
changes have been done to the the file, but is generally not a requirement.

Signed-off-by: Mike Belopuhov <mike.belopuhov@esdenera.com>