passpoint-r2: add OSU flag for WifiInfo

This flag is required for UI to handle it differently for OSU AP.

Bug: 122321935
Test: ./frameworks/base/wifi/tests/runtests.sh
Test: testing on UI by clicking OSU provider name.
Change-Id: I6d31f093a9d7fb0b768cd105f270ac54beec9b2d
Signed-off-by: Ecco Park <eccopark@google.com>