chromeos_config: remove x86-generic-*

Remove all x86-generic-* boards.

BUG=chromium:729645
TEST=chromeos_config_unittest

Change-Id: I83bf8130a4571113126a48156a805ab15c01aacf
Reviewed-on: https://chromium-review.googlesource.com/588081
Commit-Ready: Paul Hobbs <phobbs@google.com>
Tested-by: Paul Hobbs <phobbs@google.com>
Reviewed-by: Paul Hobbs <phobbs@google.com>
19 files changed