kexec: load-preserve-context option on s390

[Michael Holzheu]

Hello Simon,

I think the --load-preserve-context and --load-jump-back-helper kexec
options are not working on s390 because we do not support
CONFIG_KEXEC_JUMP. I assume the same is true also on other
architectures. Correct me, if I am wrong. Unfortunately I did not find
much documentation for that feature.

Wouldn't it be better to print an error message when the options are
used on those architectures?

Michael