Bluetooth: Add SPDX id lines to some source files

Bluetooth: Add SPDX id lines to some source files

Many bluetooth source files are missing SPDX-License-Identifier
lines. Add appropriate IDs to these files, and remove other
license lines from the headers.

Leave the warranty disclaimer in files where the license ID is
GPL-2.0 but the wording of the disclaimer is slightly different
from that of the GPL v2 disclaimer.

It is not different enough to cause licensing conflicts, but is
kept to honor the original contributors' legal intent.

Signed-off-by: Tim Bird <tim.bird@sony.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>