WifiInstaller: use updated PasspointConfiguration APIs

PasspointConfiguration APIs are updated to use private
variables with public accessor methods instead of public variables.
So update the code to use the accessor methods instead of using
variables directly.

Bug: 34627062
Test: make -j32
Change-Id: I96e06a16440eba02ea2d39db1ef5a0e5016e0f7a
1 file changed