cpu/stm32: consider starting white spaces in gen_vectors.py
cpu/stm32: consider starting white spaces in gen_vectors.py

In some CMSIS headers, "typedef enum" could be preceded by white
spaces. Thus consider them when parsing the line.

Signed-off-by: Gilles DOFFE <5872090fc9813271e12cf6b5c9dea3d3f95dd463@savoirfairelinux.com>

kYc0o/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,kaspar030/RIOT,OlegHahm/RIOT,kaspar030/RIOT,kaspar030/RIOT,kYc0o/RIOT,authmillenon/RIOT,miri64/RIOT,ant9000/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,miri64/RIOT,authmillenon/RIOT,kYc0o/RIOT,OlegHahm/RIOT,miri64/RIOT,OlegHahm/RIOT,ant9000/RIOT,jasonatran/RIOT,authmillenon/RIOT,OTAkeys/RIOT,miri64/RIOT,kaspar030/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,jasonatran/RIOT,authmillenon/RIOT,miri64/RIOT,kaspar030/RIOT,kYc0o/RIOT,jasonatran/RIOT,kYc0o/RIOT,ant9000/RIOT,jasonatran/RIOT,ant9000/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,ant9000/RIOT,OTAkeys/RIOT