Add eARC info to HdmiPortInfo

Add a stub for the earcSupported parameter to HdmiCecController. The
HDMI HAL methods (such as getPortInfo, the method that reports this
parameter) currently enter the framework through HdmiCecController, but
may be moved out into a separate controller in the future.

Test: make
Bug: 240388203
Change-Id: I231cd4ed97490d6770c45b0fd5631274c421b672