SMB3: Add handling for different FSCTL access flags

DesiredAccess field in SMB3 open request needs
to be set differently for READ vs. WRITE ioctls
(not just ones that request both).

Originally noticed by Pavel

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>