staging: line6: drop pod.c raw sysfs attr

The raw sysfs attr transmits MIDI messages with less filtering.  This
was a useful debugging tool while the staging driver still had a lot of
state and filtering.  It is not useful anymore since the filtering is
being dropped.

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