uia: remove redundant component registration.

Change-Id: I913e6498d09021cca78be27b542421251f258535
uia: move accessibility init into component to avoid platform conditionals

Code from Steve Yin <steve_y@apache.org>, "Integrate branch of IAccessible2"

Change-Id: Ib19e38ddca71182018df438df27dcdb555d91402