cifs: update desired access while requesting for directory lease

We read and cache directory contents when we get directory
lease, so we should ask for read permission to read contents
of directory.

Signed-off-by: Bharath SM <bharathsm@microsoft.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>