Floss: Clean up stack on shut down

When the adapter is shut down, we should also clean up the
instance to ensure all the modules get shut down.

This fixes a bug where the storage module wasn't getting shut
down leading to device info not being saved if bluetooth was
immediately toggled off afterward.

Bug: 288636142
Tag: #floss
Test: emerge-brya floss and confirm forget persists after BT off
Test: mma -j32
Change-Id: I37a7a16c861838c3a23bef005352709f45c1348b