Closing the HAB socket correctly in unmount scenarios

This change is required for the VM restart mechanism where the
unclosed HAB socket will block the reboot of the GVM.

Change-Id: I4c84e65d981bc1bb09e943dc6985217d3407e9ab
Acked-by: Sriragh Karat <skarat@qti.qualcomm.com>
Signed-off-by: Bojun Pan <bojunp@codeaurora.org>