CVE-2025-39742

In the Linux kernel, the following vulnerability has been resolved:

RDMA: hfi1: fix possible divide-by-zero in find_hw_thread_mask()

The function divides number of online CPUs by num_core_siblings, and
later checks the divider by zero. This implies a possibility to get
and divide-by-zero runtime error. Fix it by moving the check prior to
division. This also helps to save one indentation level.