Whitelist minui properties to be overridden by /vendor/default.prop.

These values will be read by platform module (/sbin/charger), and need
to be configurable by vendor init.

Bug: 113567255
Test: Build along with other CLs in the topic (for Makefile and
      libminui changes). Boot into charger mode.
Test: Boot into recovery. Run graphics test.
Change-Id: I5b272f345e2a5a255c2f660c59c1da3245aa1e03