Simplify make-image-header.sh call and make sure it gets called in
the current working directory. Also check the return value of the
function call.
(From OE-Core rev: d4c55e2448053b51eb217c61328a2ca25bec0461)
Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>