icnss2: Clear driver ops during driver unload

As part of wlan driver unload wlan driver is freeing driver
ops memory on its side. ICNSS driver doesn't call wlan driver
remove if it is not probed. So, In some cases when wlan driver
has not been probed and driver unload comes,icnss driver doesn't
clears driver ops on its side which leads of freed memory
access on its side. This change clears wlan driver ops during
driver unload if wlan driver is not probed.

Change-Id: I43e384622a6d5ec8d82a2e9fdea1639055e07829
Signed-off-by: Sandeep Singh <sandsing@codeaurora.org>