msm: mdss: hdmi: hdcp: load keys separately before authentication

Retrieve and load the HDCP keys before starting authentication so
that HDCP internal state machine can be initialized completely on
cable connection to avoid possible authentication failures.

Change-Id: I873fb02589bb6c19938743d44dc56ed1cfff7260
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>