drm: start hdcp work when the "Content Protection" was set thought atomic [1/1]

drm: start hdcp work when the "Content Protection" was set thought atomic [1/1]

PD#SWPL-4866

Problem:
1. The old implement not support atomic. (the atomic check on am_meson
hdmi.c will disable CP,The set property function will not reached when
use atomic set CP)
2. The hdcp work kthread start and terminal not match cause coredump.

Problem:
need add hdcp function.

Solution:
Start hdcp work when the encoder enabled.stop when encoder disabled.
modified hdcp work state machine.

Verify:
On u212 drm backend, use drm-helper-client to set CP property.
need enable atomic on wayland.based on below CL
http://scgit.amlogic.com:8080/#/c/78810/1
http://scgit.amlogic.com:8080/#/c/78804/2
http://scgit.amlogic.com:8080/#/c/78811/1

Change-Id: If213b7def89ff1f1ec63b866a21a3323e098786f
Signed-off-by: lingjie li <lingjie.li@amlogic.com>