Disable headercheck (copyright/license)

The current code climate headercheck uses BQA Tools which does not
recognize the Linaro copyright format (and will likely not recognize
other contributors). This is causing unnecessary code quality warnings
about copyright dates when the Arm copyright notice is not the latest.

Regardless, for this project, we should only be enforcing license. It's
up to contributors to decide what copyright (if any) they want to
assert.

Disable the headercheck until BQA Tools can be fixed or a more flexible
replacement found.

Changelog: other
Signed-off-by: Adam Johnston <adam.johnston@linaro.org>