stm32_common/flashpage: cleanup stm32l0/1
stm32_common/flashpage: cleanup stm32l0/1

- Since writes are performed per word no actions need
  to be performed for flash access, and the FPRG doesn't
  need to be cleared.

OTAkeys/RIOT,miri64/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,rfuentess/RIOT,kaspar030/RIOT,smlng/RIOT,OTAkeys/RIOT,rfuentess/RIOT,authmillenon/RIOT,cladmi/RIOT,miri64/RIOT,toonst/RIOT,mtausig/RIOT,josephnoir/RIOT,kYc0o/RIOT,OTAkeys/RIOT,kaspar030/RIOT,miri64/RIOT,cladmi/RIOT,aeneby/RIOT,smlng/RIOT,aeneby/RIOT,basilfx/RIOT,RIOT-OS/RIOT,josephnoir/RIOT,OlegHahm/RIOT,josephnoir/RIOT,OTAkeys/RIOT,jasonatran/RIOT,yogo1212/RIOT,kYc0o/RIOT,kaspar030/RIOT,cladmi/RIOT,ant9000/RIOT,smlng/RIOT,toonst/RIOT,cladmi/RIOT,josephnoir/RIOT,yogo1212/RIOT,yogo1212/RIOT,smlng/RIOT,rfuentess/RIOT,authmillenon/RIOT,kYc0o/RIOT,authmillenon/RIOT,x3ro/RIOT,basilfx/RIOT,authmillenon/RIOT,toonst/RIOT,jasonatran/RIOT,mtausig/RIOT,toonst/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,aeneby/RIOT,kYc0o/RIOT,aeneby/RIOT,OlegHahm/RIOT,rfuentess/RIOT,x3ro/RIOT,kaspar030/RIOT,OlegHahm/RIOT,jasonatran/RIOT,rfuentess/RIOT,ant9000/RIOT,yogo1212/RIOT,authmillenon/RIOT,josephnoir/RIOT,x3ro/RIOT,x3ro/RIOT,ant9000/RIOT,kYc0o/RIOT,smlng/RIOT,jasonatran/RIOT,miri64/RIOT,authmillenon/RIOT,yogo1212/RIOT,mtausig/RIOT,OTAkeys/RIOT,x3ro/RIOT,kaspar030/RIOT,basilfx/RIOT,aeneby/RIOT,ant9000/RIOT,OlegHahm/RIOT,cladmi/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,ant9000/RIOT,mtausig/RIOT,jasonatran/RIOT,basilfx/RIOT,basilfx/RIOT,miri64/RIOT,toonst/RIOT,mtausig/RIOT