Fix double tap power key to launch camera locks phone

If user enabled double tap power to launch camera, we should return the
correct value of 'MaxMultiPressPowerCount' so single tap power detector
could wait for multi press timeout instead triggering 'powerPress'
immediately.

Test: double tap power to launch camera
Bug: 188247996
Change-Id: I4ca28c42c4affd9c48219e3c68630ea0ce1d5409