cpu/stm32_common/uart: fix typos in rts/cts pins
cpu/stm32_common/uart: fix typos in rts/cts pins

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