CVE-2026-31569 LoongArch: KVM: Handle the case that EIOINTC's coremap is empty

In the Linux kernel, the following vulnerability has been resolved: LoongArch: KVM: Handle the case that EIOINTC's coremap is empty EIOINTC's coremap in eiointcupdateswcoremap can be empty, currently we get a cpuid with -1 in this case, but we actually need 0 because it's similar as the case that...