CVE-2026-31559 LoongArch: Fix missing NULL checks for kstrdup()

In the Linux kernel, the following vulnerability has been resolved: LoongArch: Fix missing NULL checks for kstrdup 1. Replace "offindnodebypath"/"" with "ofroot" to avoid multiple calls to "ofnodeput". 2. Fix a potential kernel oops during early boot when memory allocation fails while parsing CPU...