lib: Add SPDX License Identifier

lib: Add SPDX License Identifier

This patch adds SPDX License Identifier and removes the license text.

-------------------------------------
       License            COUNT
-------------------------------------
 GPL-2.0-or-later     :     18
 GPL-2.0-only         :      1

License: GPL-2.0-or-later
   lib/sco.h
   lib/sdp.c
   lib/a2mp.h
   lib/uuid.h
   lib/bluetooth.h
   lib/hidp.h
   lib/rfcomm.h
   lib/hci.c
   lib/sdp.h
   lib/sdp_lib.h
   lib/bluetooth.c
   lib/mgmt.h
   lib/hci.h
   lib/uuid.c
   lib/l2cap.h
   lib/bnep.h
   lib/hci_lib.h
   lib/cmtp.h

License: GPL-2.0-only
   lib/amp.h

Signed-off-by: Anuj Jain <anuj01.jain@samsung.com>
Signed-off-by: Ayush Garg <ayush.garg@samsung.com>