KVM: don't pointlessly leave KVM_COMPAT=y in non-KVM configs

The symbol was missing a KVM dependency.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

virt/kvm/Kconfig

@@ -46,7 +46,7 @@ config KVM_GENERIC_DIRTYLOG_READ_PROTECT
 
 config KVM_COMPAT
        def_bool y
-       depends on COMPAT && !S390
+       depends on KVM && COMPAT && !S390
 
 config HAVE_KVM_IRQ_BYPASS
        bool