staging: line6: drop pod prog_data buffers

The driver no longer keeps state of MIDI-accessible device parameters.
Drop the buffers but be careful to keep the device startup procedure
working even though we no longer store the contents of the dump request.
The startup procedure will be simplified in a later patch.

Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>