Added sysfs to force phone into user selectable pogo dock modes when
pogo GPIO detection fails. Useful for homemade pogo docks or
touchstone charging mods.

Enable/Disable:
(Default) Disable: echo 0 > /sys/kernel/dock_mode/force_dock_mode
Enable: echo 1 > /sys/kernel/dock_mode/force_dock_mode

Dock Mode:
(Default) Desk Dock: echo 0 > /sys/kernel/dock_mode/dock_mode
Car Dock: echo 1 > /sys/kernel/dock_mode/dock_mode

Charge Mode:
(Default) AC/FastCharge: echo 0 > /sys/kernel/dock_mode/charge_mode
USB: echo 1 > /sys/kernel/dock_mode/charge_mode