DisplayGLX: factor redundant getFBConfigAttribs This is very tiny code cleanup and is a noop behavior change. BUG= Change-Id: Ib850ff88eafa0bd45bb389de1b74b1e9fe4c6d8b Reviewed-on: https://chromium-review.googlesource.com/290146 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Corentin Wallez <cwallez@chromium.org>