go-helloworld: fix license

go-helloworld: fix license

The example repo doesn't seem to have ever been under MIT.
It started with Apache-2.0, later changed to standard go license BSD-3.

The license file exists in the sources, so use that one instead of
taking it from the OE-Core license directory.

Note that this was already fixed in scarthgap and kirkstone, but it was
not submitted to master. Also the old releases still had Apache, so this
patch is different now with new versioni of thie component.

License-Update: Fix license declaration.

Signed-off-by: Peter Marko <peter.marko@siemens.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>