staging: most: dim2: enable flow control for isoc channels

This patch enables the flow control feature for the isochronous channels
of the DIM2 macro.

Signed-off-by: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>