s390/sclp: convert list_for_each to entry variant

convert list_for_each() to list_for_each_entry() where
applicable.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Link: https://lore.kernel.org/r/1623740220-15846-1-git-send-email-zou_wei@huawei.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>