Hi atheatos,
After flash via JetPack 2.3.1, I just issued below commands and then cpu1&2&3 always keep offline. FYI.
echo 0 > /sys/devices/system/cpu/cpuquiet/tegra_cpuquiet/enable
echo 0 > /sys/devices/system/cpu/cpu1/online
echo 0 > /sys/devices/system/cpu/cpu2/online
echo 0 > /sys/devices/system/cpu/cpu3/online