Revert "Bluetooth: hci_core: Fix build warnings"

This reverts commit bbec1724 which is
commit dcda1657 upstream.

It breaks the android ABI and if this is needed in the future, can be
brought back in an abi-safe way.

Bug: 161946584
Change-Id: I4a64dca20bcdfe9cbe33fc23c7d3d1b252f4b873
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>