Meanwhile one can pin PPA to prevent upgrades:
$ cat /etc/apt/preferences.d/coolpi-ppa-priority
Package: *
Pin: release o=LP-PPA-george-coolpi-mali-g610
Pin-Priority: 2000
Package: *
Pin: release o=LP-PPA-george-coolpi-multimedia
Pin-Priority: 2000
Package: *
Pin: release o=LP-PPA-george-coolpi-rknpu
Pin-Priority: 2000