Revert "PM / QoS: Use NULL pointer instead of plain integer in qos.c"

This reverts commit 25366200ed1aa8bb969ceb552c4324319d4f87c1.
Revert "PM / Sleep: Add missing static storage class specifiers in main.c"

This reverts commit d45c0bf0b967d610ff07f4b23c27c85c11c2ed6b.