commit 30c54df7 upstream.

Clear write callbacks sitting in write_waiting list on reset.
Otherwise these callbacks are left dangling and cause memory leak.
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>