staging: most: dim2-hdm: fix possible kernel freeze when reusing a dim2 channel

If a DIM2 channel is being closed while it is busy, the channels's status
flag could possibly stay active for this very channel. This causes the
kernel to freeze by the time the channel is opened again.

This patch fixes the problem.

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>