Fix uninitialized mScreenOn boolean in Clock

Fixes fail introduced from

https://github.com/TeamEOS/frameworks_base/commit/40c6915e43be05ef176023b20303827769c11dbf

Change-Id: I9daf426c588451a0a642951fba7c2d04e65acb3a
Merge remote-tracking branch 'upstream/kk4.4' into kk4.4