Add "make gen" target to regenerate em100pro_chips.h

This downloads the Windows release from dediprog.com and extracts
the per-chip data into em100pro_chips.h.  It can be used to refresh
the list when new chip types are added upstream.

"make gen" will be invoked automatically if em100pro_chips.h is
somehow absent, but it will not be invoked during a normal build from
git sources.

BUG=chromium:213898
TEST=run "make gen"

Change-Id: I703fc8332502d4731645b5c652e5b7cbb24e0e56
Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
2 files changed