boards: cpu: cleanup licenses to fix #392

Adds licenses to the following files:
```bash
boards/msba2-common/tools/src/control_2xxx.c
cpu/arm_common/atomic.s
cpu/arm_common/common.s
cpu/lpc2387/asmfunc.s
cpu/lpc2387/startup.s
```
The remaining files with "unknown" license delivered by #1181 seem to be generated automatically.
```bash
boards/msba2-common/tools/src/boot_23xx.c
boards/msba2-common/tools/src/boot_2xxx.c
```

Does anybody know about the original authors or is FU Berlin ok?