Given the setup described above you can run all of these tests with the command
atest CtsHdmiCecHostTestCases
To shard the test (distribute and run the tests on multiple devices), use this command -
./cts-tradefed run commandAndExit cts --enable-token-sharding --shard-count 3 -m CtsHdmiCecHostTestCases
The shard count corresponds to the number of DUTs connected to the host.