emulator: Add SPDX License Identifier

emulator: Add SPDX License Identifier

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

-------------------------------------
       License            COUNT
-------------------------------------
 LGPL-2.1-or-later    :     20
 GPL-2.0-or-later     :      2

License: LGPL-2.1-or-later
   emulator/server.c
   emulator/amp.c
   emulator/hciemu.c
   emulator/vhci.c
   emulator/btdev.c
   emulator/serial.h
   emulator/le.h
   emulator/le.c
   emulator/main.c
   emulator/amp.h
   emulator/hciemu.h
   emulator/bthost.h
   emulator/btdev.h
   emulator/vhci.h
   emulator/serial.c
   emulator/phy.c
   emulator/smp.c
   emulator/phy.h
   emulator/bthost.c
   emulator/server.h

License: GPL-2.0-or-later
   emulator/b1ee.c
   emulator/hfp.c

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