CVE-2026-52985 netdevsim: zero initialize struct iphdr in dummy sk_buff

In the Linux kernel, the following vulnerability has been resolved: netdevsim: zero initialize struct iphdr in dummy skbuff Syzbot reports a KMSAN uninit-value originating from nsimdevtrapskbbuild, with the allocation also being performed in the same function. Fix this by calling skbputzero inste...