secrets: vault.gpg: changes to vault users

Now only the following people are allowed to decrypt vault.gpg:
* charles.oliveira@linaro.org
* amro.hassaan@linaro.org
* riku.voipio@linaro.org
* ben.copeland@linaro.org
* kelley.spoon@linaro.org

Signed-off-by: Charles Oliveira <charles.oliveira@linaro.org>

Author: chaws