msm: mdss: hdcp2p2: fix check for sink support for HDCP 2.x

Current implementation only checks if the sink is HDCP capable.
In addition, it is required that the source also checks for the
HDCP version supported by the sink prior to initiating HDCP 2.x
authentication sequence.

CRs-Fixed: 2062951
Change-Id: I24901202a0abc2ff4336ab9c6c2fd708a53559f2
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>