Remove redundant blank line which is left by Commit 662770af,
also take this opportunity to remove redundant includes in dirtyrate.c.

Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Message-Id: <1604030281-112946-1-git-send-email-zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>