commit f01ea0c3 upstream.

The code waiting for fifo idle was incorrect and could possibly spin
forever under certain circumstances.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reported-by: Mark Sheldon <markshel@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Reivewed-by: Mark Sheldon <markshel@vmware.com>
Signed-off-by: Zefan Li <lizefan@huawei.com>