Continue supporting persisting country code

Some devices rely on Setup Wizard to set a persistent country
code.
This CL honors the persistent option, fixing corresponding 5GHz AP
problem.
This also includes addtional unit tests for this change.

BUG=28127280
TEST=compile
TEST=runtest frameworks-wifi
Change-Id: I2f36216e143d0ac4959f26a9965def061a06aabf
4 files changed
tree: 622538c5fb4791f915f3d2931b36d2d028c11f39
  1. service/