Idle Job Start During SCREEN_ON or DREAMING_STOPPED

When the screen goes off or dreaming start, an alarm will be
scheduled and idle state will be true when the alarm expired.
If the screen goes on or dreaming stop happens before
the alarm expired, the alarm isn't cancelled and idle state is
set to be true when the device is in SCREEN_ON or DREADING_STOPPED
state. There is also a case that Idle alarm triggered when
the screen on or dreaming stop just start to be processed.
ACTION_TRIGGER_IDLE will set mIdle to true during screen on
or dreaming stop.

In this patch, the alarm will be cancelled when the screen goes
on or dreaming stop and screen-on flag will be set. So the idle
state can only be set when screen is off or dreaming started.

Change-Id: I06ae4b7fd77901f9570ce0459d2299bbfd4b46b4