sandbox: Implement the bootm command for sandbox

When sandbox does a 'bootm' to run a kernel we cannot actually execute it.
So just exit sandbox, which is essentially what U-Boot does on other archs.
Also, allow sandbox to use bootm on any kernel, so that it can be used
to test booting of kernels from any architecture.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
1 file changed