Allow properties to be derived from partition-specific properties during init

If not present, ro.product.[brand|device|manufacturer|model|name] and
ro.build.fingerprint will be resolved during init from
partition-specific properties.

Test: booted system image, verified properties
Test: booted recovery image, verified properties
Bug: 120123525
Change-Id: I7fe2793a7d9eb65645d92ceb408f1f050acf9a81