CVE-2026-72011 s390/diag: Add missing array_index_nospec() call to memtop_get_page_count()

In the Linux kernel, the following vulnerability has been resolved: s390/diag: Add missing arrayindexnospec call to memtopgetpagecount 'level' is user space controlled and used to read from an array. Add the missing arrayindexnospec call to prevent speculative execution...