Add Apache License header. Not sure why this was omitted.
Add Apache License header. Not sure why this was omitted.

X-Original-Commit: dd79d9310ae84e9f7090ab09141f9916f2c2e102

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble