ClientModeImpl: Get the connecting network config on failure

getCurrentWifiConfiguration() returns null on connection failure, so
retrieve the WifiConfiguration for the connecting network on connection
failure.

Bug: 127794702
Test: ./frameworks/opt/net/wifi/tests/wifitests/runtests.sh
Change-Id: I18f9432a9e33bcdaa3a678f5700744e06aee6c4d
2 files changed