Split networkDestroy() and destroyNetworkCache()

When an exception occurs while executing networkDestroy(),
destroyNetworkCache() is not executed and
destroyNativeNetwork() is terminated. Eventually,
this leads to the problem of netid not being properly organized.
It makes UE not able to send/receive MMS or use the internet until
rebooting.

Test: Build Pass, make force exception manually

Signed-off-by: Wangkeun Oh <wangkeun.oh@samsung.com>
Change-Id: I3dea967948ebda7b1c1f601c8ffa6e736b666c4c