Additional log for when power is pressed

Add a log for when powerPress is called with the details of the
invocation.

Bug: 66509762
Test: press power key, observe logcat.
When display is ON:
powerPress: eventTime=338021489 interactive=true count=1 beganFromNonInteractive=false mShortPressOnPowerBehavior=1
When display is OFF:
Not invoked

Change-Id: Ief6d9e3fe0c1bf2a67c90680000359d040d55b2a