Process eARC status updates from HAL

Also inform the HDMI HAL which hotplug signal it should use for features
other than eARC, e.g. EDID updates. When eARC is enabled, eARC uses the
physical HPD signal and the other applications need to use the HPD bit
instead.

Bug: 260547935
Test: make and atest

Change-Id: I7dc17270a16ece368d6db6e3674108f960fad63b