By using utilities in bitops and bitmap, this patch tries to make it more
friendly to audience. No functional change.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Message-Id: <1457229445-25954-1-git-send-email-richard.weiyang@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>