staging: unisys: visornic: remove visornic_poll prototype

Remove visornic_poll prototype, because it is not needed.

Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <Timothy.Sell@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>