CVE-2026-89981 arm64: Don't read GMID_EL1 when MTE is disabled

In the Linux kernel, the following vulnerability has been resolved: arm64: Don't read GMIDEL1 when MTE is disabled cpuinfostorecpu gates the GMIDEL1 read on the raw IDAA64PFR1EL1, so it reads the register even when the kernel has disabled MTE CONFIGARM64MTE=n or arm64.nomte. KVM sets HCREL2.TID5 ...