It easily let people think of "the window now is 4096 which is
shrinked", but the truth is the value actually didn't change (4096).
Let's only dump this message if the value really changed, and we make
the message even simpler like:
kvm_ple_window: vcpu 4 old 4096 new 8192 (growed)
Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>