Yoda conditions lack readability, and QEMU has a
strict compiler configuration for checking a common
mistake like "if (dev = NULL)". Make it a written rule.
Signed-off-by: NGonglei <arei.gonglei@huawei.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>