adding/updating license to GPL3

targets/ARCH/COMMON/COPYING

targets/ARCH/COMMON/common_lib.h

targets/ARCH/EXMIMO/DEFS/COPYING

targets/ARCH/EXMIMO/DEFS/openair_device.h

targets/ARCH/EXMIMO/DEFS/pcie_interface.h

targets/ARCH/EXMIMO/DRIVER/eurecom/COPYING

targets/ARCH/EXMIMO/DRIVER/eurecom/defs.h

targets/ARCH/EXMIMO/DRIVER/eurecom/exmimo_fw.c

targets/ARCH/EXMIMO/DRIVER/eurecom/extern.h

targets/ARCH/EXMIMO/DRIVER/eurecom/fileops.c

targets/ARCH/EXMIMO/DRIVER/eurecom/irq.c

targets/ARCH/EXMIMO/DRIVER/eurecom/module_main.c

targets/ARCH/EXMIMO/DRIVER/eurecom/vars.h

targets/ARCH/EXMIMO/DRIVER/exmimo3/COPYING

targets/ARCH/EXMIMO/DRIVER/exmimo3/defs.h

targets/ARCH/EXMIMO/DRIVER/exmimo3/exmimo_fw.c

targets/ARCH/EXMIMO/DRIVER/exmimo3/extern.h

targets/ARCH/EXMIMO/DRIVER/exmimo3/fileops.c

targets/ARCH/EXMIMO/DRIVER/exmimo3/irq.c

targets/ARCH/EXMIMO/DRIVER/exmimo3/module_main.c