ANDROID: sched: Add trace hook for DL server

Create a trace hook when the DL server is activated.
This allows vendors to debug RT/Fair contention issues
by dumping the following information:

1.The task served by the DL server
2.The status of the DL server

Bug: 436885337

Change-Id: I2157bd22b7d7c80d7ec1eeeba3ec6fb88efa4abd
Signed-off-by: kuyo chang <kuyo.chang@mediatek.com>
Signed-off-by: kuyo chang <kuyo.chang@mediatek.corp-partner.google.com>