msm: mdss: hdmi: hdcp2p2: add tethered support

Provide user an option to let the HDCP2.2 authentication
run on main thread. Avoid processing on module threads
thus avoiding any scheduling delays. The user may choose
to switch to this mode based on its requirements.

Change-Id: I76ec4a18f0fc52e99bbe76b6707511d3af6151f3
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>