staging/olpc_dcon: drop useaa module arg

The 'useaa' module parameter was a workaround for a buggy DCON prototype
not supporting the optional anti-aliasing mode properly.  There's no
reason to disable it any more, so drop the option.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>