cpu/esp8266: Moved stdio_init before periph_init
cpu/esp8266: Moved stdio_init before periph_init

- This guarantees that DEBUG() is available early in boot process
- Forgotten in https://github.com/RIOT-OS/RIOT/pull/11367, this fixes broken stdio

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