icnss: Remove the driver while device is going to shutdown

Power down sequence of wlan is not proper which leads to
toggling of SW_CTRL line during system shutdown and system
restart. Hence, to avoid the SW_CTRL toggling issue remove
the driver during system shutdown and system restart.

Change-Id: I1213fdca16cbf5942af21633d721ff1ff03fedaa
Signed-off-by: Sandeep Singh <sandsing@codeaurora.org>