staging: line6: drop CONFIG_LINE6_USB_RAW

Now that both pod.c and variax.c have removed their raw sysfs attrs, the
CONFIG_LINE6_USB_RAW config option can be dropped.  The drivers are
being stripped down to just PCM and MIDI I/O so there is less state and
filtering.  Therefore it's no longer necessary to have a special sysfs
attr to bypass the filtering ("raw").

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