HDMI: Add dumpsys info for active source caller

Partner reported it is difficult to tell active source client, adding a
line in hdmi dumpsys to make it clear. Given it is for debugging
purpose, we only store the last three caller.

Test: test on device and verify by partner
Bug: b/436125596
Flag: EXEMPT minor feature update w/ no api change

Change-Id: I5d6821f883e3eefa3cfbcabc2a74bc9dcc6a5e65