Staging: line6: only allocate a buffer if it is needed

Only allocate the version request buffer if it is needed, not when the
module starts up.  This will let us make the module_init path much
smaller.

CC: Markus Grabner <grabner@icg.tugraz.at>
CC: Stefan Hajnoczi <stefanha@gmail.com>
CC: Julia Lawall <julia@diku.dk>
CC: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>