octeontx2-af: fix out-of-bounds read setting MSI-X irq affinity

In the Linux kernel, the following vulnerability has been resolved: octeontx2-af: fix out-of-bounds read setting MSI-X irq affinity rvu_register_interrupts() walks every MSI-X vector and uses strstr() to match "Mbox" or "FLR" in irq_name before pinning those interrupts to CPU 0. irq_name is a per-vector NAME_SIZE buffer, but not every slot is populated before this loop runs. strstr() keeps scanning until it finds a NUL terminator, so an uninitialized slot can trigger a KASAN slab-out-of-bounds read at boot when debug options are enabled. Use strnstr() with NAME_SIZE to bound the search within each vector's name buffer.