classes/kernel: Use a copy of image for kernel*.rpm if fs doesn't support symlinks
Some filesystems don't support symlink, then you will get failure when
you install or update the kernel rpm package. Now we use a copy of
image for these filesystems instead of symlink.
Suggested-by: Bruce Ashfield <bruce.ashfield@gmail.com> Suggested-by: Richard Purdie <richard.purdie@linuxfoundation.org> Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
