dlx: use new offmode_charging and images

HTC incorporated charger functionality into offmode_charging and added
1% increment images. This makes offmode charging look much nicer. Also,
bring back detect_key and power_test so that the power button works to
turn-on the device from offmode.

Blobs from dlx 4.09.605.1.

Change-Id: I98cf319e93f143f5eda85f35038f3f21024f208b