wifi: Rename API convertChannelToFrequencyMhz/convertFrequencyMhzToChannel

API review comments:
convertChannelToFrequencyMhzIfSupported and keeping UNSPECIFIED sgtm

Bug: 181661717
Test: atest -c FrameworksWifiTests
Test: atest -c FrameworksWifiApiTests

Change-Id: I3273c41c4497b433d5543ade7386ceaa65a76900
9 files changed