CVE-2026-53174 ovl: keep err zero after successful ovl_cache_get()

In the Linux kernel, the following vulnerability has been resolved: ovl: keep err zero after successful ovlcacheget ovliteratemerged stores PTRERRcache in err before checking ISERRcache. On success err holds the truncated cache pointer and can be returned as a bogus non-zero error. The syzbot...