recovery: Remove duplicate variables and functions

The function that modifies rtl_locale exists only in the base class,
and so the variable should not have a duplicate in the derived class,
otherwise there may be incosistent values when it is read by the derived
class (the thinking being that invoking the function will modify the
base class version of the variable, and not the derived class version).

Remove the updateMutex variable, and instead re-use the one in the base
class.

Also remove LoadBitmap from WearUI since it is identical to the one in
ScreenRecoveryUI.

Bug: 27407422
Change-Id: Idd823fa93dfa16d7b2c9c7160f8d0c2559d28731