staging: line6: Index properties array with device type

The current logic uses the index of the matched entry from the device
table as an offset to the corresponding properties entry.  The values
of the new `line6_device_type' enum are ordered such that they can be
used as an index into either of these arrays.  Drop the device entry
lookup logic and use the device type (via the .driver_info member)
instead.

Signed-off-by: Chris Rorvick <chris@rorvick.com>
Reviewed-by: Stefan Hajnoczi <stefanha@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>