In case of func->state or func->old_addr not having expected values,
we'd rather bail out immediately from klp_disable_func().

This can't really happen with the current codebase, but fix this
anyway in the sake of robustness.

[jkosina@suse.com: reworded the changelog a bit]
Signed-off-by: NMinfei Huang <mnfhuang@gmail.com>
Acked-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NJiri Kosina <jkosina@suse.com>