StatusBarSettings: Correct clock position setting label in RTL

If the device is set to RTL (right-to-left), then the statusbar clock
settings say "left" and mean "right" and vice versa.

Only the label texts should be swapped in RTL, not the item IDs, because
the items have "end/center/start" semantics and not "right/center/left".

Change-Id: I436ae7e162d0f00873090143822a5c69a35d2e06