Crash/Reboot with v31 when entering sleep mode

[mfuerstenau]

1. Installed 41.2.A.7.76 (different images also tested)
2. Booted. Everything works normal.
3. Flashed "boot" partition with v31.
4. Booted. Everithing okay, as long sleep mode not entered.
5. Locking screen, entering sleep -> crash/reboot (happens everytime).

Reboot/crash happens also if I do not enter password for decryption and just wait, thus entering a reboot loop.

Just a wild guess: changes to drivers/cpuidle/lpm-levels.c may have caused this.