Change recovery to static platform-only compilation.

Recovery is not meant to be versioned in the treble model, but rather
provided as part of the platform/framework component and self-sufficient.
Simplify its compilation by removing the attribute versioning steps, but
maintain device-specific policy, which is currently required for full
functionality.

Bug: 37240781
Bug: 36783775
Test: recovery boots and is able to select commands.  Also tried:
reboot system, boot to bootloader, factory reset, sideload, view logs,
run graphics test, and power off.

Change-Id: I637819844d9a8ea5b315404f4abd03e8f923303a