cpu/mips32r2_common: Added call to stdio_init()
cpu/mips32r2_common: Added call to stdio_init()

Fixed bug introduced in https://github.com/RIOT-OS/RIOT/pull/11367

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