MIPS: mm: Fix out-of-bounds write in maar_res_walk()

In the Linux kernel, the following vulnerability has been resolved: MIPS: mm: Fix out-of-bounds write in maar_res_walk() maar_res_walk() uses wi->num_cfg as the index into the fixed-size wi->cfg array, but checks whether the array is full only after it has filled the selected entry. If walk_system_ram_range() reports more than 16 memory ranges, the overflow call writes one struct maar_config past the end of the array before WARN_ON() prevents num_cfg from advancing. Move the full-array check before taking the array slot and return non-zero when the scratch array is full, so walk_system_ram_range() terminates the walk instead of invoking the callback for further ranges.