This fixes a minor lint/style issue, improves consistency. According to Go style, which this project follows, acronyms should have a consistent case. Source: https://github.com/golang/go/wiki/CodeReviewComments#initialisms See https://github.com/docker/docker/pull/11310#discussion_r67394302. Signed-off-by: Dmitri Shuralyov <shurcooL@gmail.com> Upstream-commit: 8cf4133f3749d7fa99a56cde98676a161971fb71 Component: engine