staging: most: remove redundant call to wake_up_interruptible

This patch prevents the cdev module from rousing the channel wait queue in
case the channel is about to be closed. It is safe to do so, because the
application can not be waiting within read or write and at the same time
be calling close.

Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>