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

In CL:368110 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:368110,CL:368051

Change-Id: If02cc0990a102479854b08000255dd8acd3f83ce
Reviewed-on: https://chromium-review.googlesource.com/368120
Commit-Ready: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed