cnss2: Destroy QMI handle when QMI service exits

Currently QMI handle will be leaked when QMI service disconnects
since new handle will be created when reconnection happens. Destroy
it to avoid the leak.

Change-Id: Ic715ce6b86dcb646d7c7312cb811e57145e1337c
Signed-off-by: Yue Ma <yuem@codeaurora.org>