Update USb preference controller to use the new summary texts.

- since the choose usb mode dialog and the preference summary use
separate strings now, the two classes can have their own handling
for getting the title/summary text and hence revert the earlier
change that move the setTitle() and setSummary() from the activity
to controller
- only show summary for the option for "supply power", and don't set
summary for all other options
- update the controller to use the new summary text.
- update test correspondingly.

Change-Id: Ie56eb33ba24262e6f3a2259e4ee5ad6f3bfb8061
Fix: 36234108
Test: make RunSettingsRoboTests