CIFS: Do not set credits to 1 if the server didn't grant anything

commit 33fa5c8b upstream.

Currently we reset the number of total credits granted by the server
to 1 if the server didn't grant us anything int the response. This
violates the SMB3 protocol - we need to trust the server and use
the credit values from the response. Fix this by removing the
corresponding code.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>