tests/unittests: enable boards with enough memory
tests/unittests: enable boards with enough memory

Now that tests with packages have been moved out of `unittests`
re-enable boards with enough memory.

The removed boards list matches the boards that now compiled locally
with `BUILD_IN_DOCKER=1 make buildtest` and also the output of murdock
for boards that were able to link despite being in the list:

    avsextrem:gnu
    cc2538dk:gnu
    firefly:gnu
    mbed_lpc1768:gnu
    msba2:gnu
    openmote-b:gnu
    openmote-cc2538:gnu
    remote-pa:gnu
    remote-reva:gnu
    remote-revb:gnu
    seeeduino_arch-pro:gnu

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