staging: line6: add missing MIDI postprocessing case for POD HD300
The driver leaves MIDI processing up to userspace for the POD HD300
device. Add a missing case statement to skip MIDI postprocessing in the
driver. This change has no effect other than silencing a printk:
line6usb driver bug: missing case in linux/drivers/staging/line6/midi.c:179
Signed-off-by: Stefan Hajnoczi <stefanha@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>