make_netboot: Change use flags to right name 'factory_netboot_ramfs'.

In CL:374200 the netboot_ramfs USE flag is changed to
factory_netboot_ramfs, and the netboot builder script should use the new
name.

BUG=chromium:477744
TEST=./make_netboot.sh
CQ-DEPEND=CL:374200,CL:374878

Change-Id: Ibae0532b80afaf7aaaa9f4aa506fa4f7641187fe
Reviewed-on: https://chromium-review.googlesource.com/374400
Commit-Ready: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
(cherry picked from commit ff887dee55ed745fc159fab1ce0b1bc0328828ac)
Reviewed-on: https://chromium-review.googlesource.com/414847
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Commit-Queue: Hung-Te Lin <hungte@chromium.org>
Trybot-Ready: Hung-Te Lin <hungte@chromium.org>
1 file changed