s390/smp: __smp_rescan_cpus() - move cpumask away from stack

stable inclusion
from stable-5.10.24
commit e4b98e2260fd47208fda30d5e182d790941a9332
bugzilla: 51348

--------------------------------

[ Upstream commit 62c8dca9 ]

Avoid a potentially large stack frame and overflow by making
"cpumask_t avail" a static variable. There is no concurrent
access due to the existing locking.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by:   Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>