libexternal: Remove setExternalDisplay function call

Calling setExternalDisplay in setActionSafeDimension
is leading to WFD session disconnect.

Crs-Fixed: 495062
Change-Id: I7a6ea0d668d4447d59ed0a7a0ac442327d019b71
hotplug OFFLINE event should be sent

In case of HDMI is plugged when WFD session was going on
hotplug OFFLINE event should be sent to framework

CRs-fixed: 519796

Change-Id: I3600ee6b1ba18539da106c45c3f084f1c825b260