staging: ozwpan: use tasklet_kill in device remove/release process

Some driver uses tasklet_disable in device remove/release process,
tasklet_disable will inc tasklet->count and return. If the tasklet
is not handled yet under some softirq pressure, the tasklet will be
placed on the tasklet_vec, never have a chance to be excuted. This might
lead to a heavy loaded ksoftirqd, wakeup with pending_softirq, but
tasklet is disabled. tasklet_kill should be used in this case.

Signed-off-by: Xiaotian Feng <dannyfeng@tencent.com>
Cc: Rupesh Gujare <rgujare@ozmodevices.com>
Cc: Chris Kelly <ckelly@ozmodevices.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>