Revert "s390/smp: enforce lowcore protection on CPU restart"

Revert "s390/smp: enforce lowcore protection on CPU restart"

BugLink: https://bugs.launchpad.net/bugs/1990162
commit 953503751a426413ea8aee2299ae3ee971b70d9b upstream.

This reverts commit 6f5c672d17f583b081e283927f5040f726c54598.

This breaks normal crash dump when CPU0 is offline.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>