mips: Report an error when KVM_VM_MIPS_VZ is unavailable

On MIPS, QEMU requires KVM_VM_MIPS_VZ type for KVM. Report an error in
such a case as other architectures do when an error occurred during KVM
type decision.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20230727073134.134102-4-akihiko.odaki@daynix.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

target/mips/kvm.c

@@ -1278,6 +1278,7 @@ int kvm_arch_get_default_type(MachineState *machine)
     }
 #endif
 
+    error_report("KVM_VM_MIPS_VZ type is not available");
     return -1;
 }