ksmbd: fix wrong error response status by using set_smb2_rsp_status()

ksmbd: fix wrong error response status by using set_smb2_rsp_status()

[ Upstream commit be0f89d4419dc5413a1cf06db3671c9949be0d52 ]

set_smb2_rsp_status() after __process_request() sets the wrong error
status. This patch resets all iov vectors and sets the error status
on clean one.

Fixes: e2b76ab8b5c9 ("ksmbd: add support for read compound")
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>