The absence of signing_key.* in $kerneldir made signing of
out-of-tree kernel modules fail (silently). Add copying of these
files during the shared_workdir task.
(From OE-Core rev: 7aadc91b5ef86a89a827d59bd19e7b8272a5dd66)
Signed-off-by: Mattias Waldo <mattias.waldo@saabgroup.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>