Revert "Bluetooth: hci_core: Fix use-after-free in vhci_flush()"

This reverts commit ce23b73f which is
commit 1d612310 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Id61431c9decd8e97b69d0a3871b2658242c092ee
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>