Some targets like kirkwood or omap don't use a subtarget which results
in a malformed JSON info file.
Instead of having a valid value like `"target": "ath79/tiny"` for these
targets the value is `"target": "kirkwood/"`.
This patch uses the same if condition to use `generic` if the subtarget
is empty.
Tested for the kirkwood target.
Signed-off-by: Paul Spooren <mail@aparcar.org>
73f3ad1df2