speakup ABI: Advertise synth parameters for all synths

The parameters were advertised for the "soft" synth, but they are
available for all synths.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Link: https://lore.kernel.org/r/20210128180116.1848120-2-samuel.thibault@ens-lyon.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>